LBOI
Landolt-Boernstein Search
  Home  |   Search  |   Indices  |   Indexed Volumes  
scidex
  
   
   
   
  
   
 Help
   No Results
Text Search:

Nickeloxid (NiO)

Compound Descriptions:

Structure Drawing
Formula:NiO
Element System:Ni-O
Element Names:Oxygen, Nickel
Molecular Weight:74.693 g/mol
Name(s):Nickeloxid
NiO
Nickel Monoxide
Nickel oxide (NiO)
Mononickel oxide
Nickel monooxide
Nickel Oxide Sinter 75
Nickel(2+) oxide
Nickel(II) oxide
Nickelous oxide
Nickelmonoxid
nickel (II) oxide
Nickel II Oxide
Nickel monoxyde
Nickel(II)-oxid schwarz
Nickel (II) oxide black
Nickel(II)oxid
Nickel oxide, nio
Nickel(II) oxide, green
Nickel(II) oxide, black
Nickel(II) Oxide Green
Nickeloxid schwarz
Nickel(II) oxide black
CAS-RN:1313-99-1, 185461-96-5, 203645-17-4
EINECS:215-215-7 EINECS
Classification:no charge; 2fragments; ionic

European Regulations

4 matching entries in european regulations: Hazard, GHS, REACH, ECHA-pre

Derivatives / Analogues

Analogueother chalcogen: NiS 
Analogueother metal: barium oxide 
Analogueother metal: Beryllia 
Analogueother metal: calcium oxide 
Analogueother metal: Cadmiumoxid 
Analogueother metal: CeO 
Analogueother metal: Kobaltoxid 
Analogueother metal: Copper oxide (CuO) 
Analogueother metal: Europiummonoxid 
Analogueother metal: iron oxide 
Analogueother metal: Mercury oxide (HgO) 
Analogueother metal: Magnesiumoxid 
Analogueother metal: Manganoxid 
Analogueother metal: niobium oxide 
Analogueother metal: Lead oxide (PbO) 
Analogueother metal: platinum oxide 
Analogueother metal: 12143-03-2 
Analogueother metal: SnO 
Analogueother metal: SrO 
Analogueother metal: titanium monoxide 
Analogueother metal: Vanadium oxide (VO) 
Analogueother metal: ZnO 

Landolt-Börnstein Citations:

Atomic Defects and Diffusion

 Chemical diffusion in bulk inhomogeneous nonmetallic compounds - Figures: Vol. III/33B1 10.3, p.56III/33B1

Crystallography, Structure and Morphology

 Simple oxides: NiO (II): Vol. III/7B1 II.1.1:1468III/7b1
 Simple oxides: NiO (I): Vol. III/7B1 II.1.1:1467III/7b1
 bulk structure and bulk lattice parameter(s): Vol. III/24c 1.6, p.24III/24C
 surface phonon energies (unspecified surface): Vol. III/24c 6.2.3, p.171III/24C
 bulk phonon dispersion curve(s): Vol. III/24c 7.2, p.314III/24C
 bulk structure and bulk lattice parameter(s): Vol. III/24d 1.6, p.24III/24D
 bulk structure and bulk lattice parameter(s): Vol. III/24a 1.6, p.24III/24a
 bulk structure and bulk lattice parameter(s): Vol. III/24b 1.6, p.24III/24b

Electrical Properties

 Elastic constants of second order: Elastic constants s, c: Vol. III/29a 1.2.1. p.74III/29a
 Elastic constants of second order: Figures: Vol. III/29a 1.3. p.388III/29a

Electronic Properties

 Transition metal compounds: Introduction: Vol. III/23b 2.6.1. p.12III/23b
 Tables and figures: Tables 1 - 3: Vol. III/23b 2.6.2. p.20III/23b
 Tables and figures: Figs. 67 - 100: Vol. III/23b 2.6.2. p.64III/23b
 Tables and figures: Figs. 36 - 66: Vol. III/23b 2.6.2. p.43-45III/23b
 Tables and figures: Figs. 67 - 100: Vol. III/23b 2.6.2. p.68III/23b

Magnetic Properties

 Descriptions of perovskite-related structures: Data: Crystallographic properties of non-ABX{3} compounds with perovskite-related structure: Vol. III/4a 3.2.4, p.193III/4a
 NiFe{3+} spinels (Ni ferrites) and NiFe{3+} spinels with substitutions: Ni ferrite NiFe{2}O{4}: Vol. III/4b 6.1.2.1, p.81III/4b
 Fe{2+}-Fe{3+}, spinels (magnetite)and Fe{2+}-Fe{3+} spinels with substitutions: Electrical properties: Vol. III/12b 4.1.1.8, p.83III/12b
 Chromium oxide spinels of Li, Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd.: ACr{2}O{4} data, compared: Vol. III/12b 4.2.1.1, p.322III/12b
 Fe-oxide spinels containing Al, Ca or Cd: Vol. III/27d 3.2.2, p.137III/27d
 Fe-oxide spinels containing Ni: Vol. III/27d 3.2.8, p.321III/27d
 Simple monoxides MO: Vol. III/27g 6.1.2.1, p.20-23III/27g
 Mixed monoxides MI1-pMIIpO: Vol. III/27g 6.1.2.2, p.30III/27g
 Diluted monoxides MpN1-pO: Vol. III/27g 6.1.2.3, p.34-36III/27g
 Simple monoxides MO: Vol. III/27g 6.1.2.1, p.4III/27g
 Simple monoxides MO: Vol. III/27g 6.1.2.1, p.17III/27g

Semiconductors

 carrier mobility, pure NiO: Vol. III/41D 3611III/41D
 optical properties, dielectric constants: Vol. III/41D 3794III/41D
 band structure: Vol. III/41D 3841III/41D
 defects in pure NiO, conductivity: Vol. III/41D 3957III/41D
 elastic moduli, heat capacity, Debye temperature: Vol. III/41D 4033III/41D
 crystal structure: Vol. III/41D 4048III/41D
 magnetic properties: Vol. III/41D 4054III/41D
 lattice parameter, thermal expansion: Vol. III/41D 4064III/41D
 phonon dispersion, phonon wavenumbers: Vol. III/41D 4089III/41D

Structure and Molecular Constants

 Molecular Constants Mostly From Microwave, Molecular Beam, Electro Spin Resonance and Sub-Doppler Laser Spectroscopy: Vol. II/24a 2.2.2:230II/24A

Thermodynamic Properties

 Elements and inorganic compounds: NH4Cl - ZnTe: Vol. IV/4 3.2.1:311, p.114IV/4
 Elements and inorganic compounds: K2PtCl4 - ZnTe: Vol. IV/4 7.2.1:1086, p.300IV/4
 Thermodynamic Properties of Compounds, NbO to S2O: Vol. IV/19a4 p.256IV/19A4

References

II/24A
Short: II/24A
Title: Molecular Constants mostly from Microwave, Molecular Beam, and Sub-Doppler Laser Spectroscopy: Rotational, l-type, Centrifugal Distortion and Related Constants of Diamagnetic Diatomic, Linear, and Symmetric Top Molecules
Author: Demaison, J.; Hübner, H.; Wlodarczak, G.
Editor: Hüttner, W.
Source: Landolt-Börnstein, New Series
Volume: II/24A
Year: 1998
Keyword: Diamagnetics Diatomics; Linear Symmetric Rotors; Molecular Constants; Molecules
ISBN: 3-540-63267-0
ISBN: 978-3-540-63267-2
Internet Resource: DOI:10.1007/b60165
RefComment: VIII, 286 pages. Hardcover
Abstract: Volume II/24 presents the spectroscopic data on diamagnetic and paramagnetic molecules as well as on molecular ions and radicals up to date considering the publications up to and partly including 1997. The spectroscopic information collected in this volume has been obtained principally from gas phase microwave measurements. Volume II/24 is a supplement to volumes II/4, II/6, II/14, and II/19 and is planned to appear in five subvolumes, the last of which will contain the substance index taking into account all molecules worked at since 1967 in the volumes mentioned and will provide cross references to and between all tables of these. The present subvolume II/24A contains the general introduction and tables of rotational and centrifugal distortion constants of diamagnetic diatomic, linear and symmetric-top molecules, i.e. data which roughly specifies the frequencies of the rotational transitions of these types of rotors.
III/12b
Short: III/12b
Title: Magnetic and Other Properties of Oxides and Related Compounds: Spinels, Fe Oxides, and Fe-Me-O Compounds
Author: Bonnenberg, D.; Hempel, K.A.; Lefever, R.A.; McGuire, T.R.; Paulus, M.; von Philipsborn, H.; Rubinstein, M.; Sugimoto, M.; Treitinger, L.; Vautier, R.
Editor: Hellwege, K.-H.; Hellwege, A.M.
Source: Landolt-Börnstein, New Series
Volume: III/12b
Year: 1980
ISBN: 3-540-09421-0
ISBN: 978-3-540-09421-0
Internet Resource: DOI:10.1007/b85783
RefComment: 1898 figs., XIV, 758 pages. Hardcover
III/23b
Short: III/23b
Title: Electronic Structure of Solids: Photoemission Spectra and Related Data
Author: Goldmann, A.; Ishii, T.; Manzke, R.; Naegele, J.R.; Skibowski, M.
Editor: Goldmann, A.
Source: Landolt-Börnstein, New Series
Volume: III/23b
Year: 1994
ISBN: 3-540-53705-8
ISBN: 978-3-540-53705-2
Internet Resource: DOI:10.1007/b91258
RefComment: 647 figs., VIII, 327 pages. Hardcover
Abstract: Photoelectron spectroscopy has matured considerably during the last decade. The experimental techniques were improved markedly. Photon line sources and,in particular, synchrotron radiation sources are now routinely available in many places. The volume summarizes data on the bulk electronic structure of solids. Besides the photoelectron results, a limited set of other data (such as lattice constants and work functions) useful in the context of band structure information is presented.
III/24C
Short: III/24C
Title: Physics of Solid Surfaces: Interaction of Charged Particles and Atoms with Surfaces
Author: Alkemade, P.; Celli, V.; Chiarotti, G.; Rocca, M.; Zanazzi, E.
Editor: Chiarotti, G.
Source: Landolt-Börnstein, New Series
Volume: III/24C
Year: 1995
ISBN: 3-540-56071-8
ISBN: 978-3-540-56071-5
Internet Resource: DOI:10.1007/b87125
RefComment: 207 figs., XII, 328 pages. Hardcover
Abstract: In the last two decades surface physics has experienced an explosive expansion caused by the development and/or substantial improvement of surface sensitive techniques and UHV appa-ratus. It has grown into a mature field of research, with data of the highest accuracy and repro-ducibility. Surface physics is of great importance for technological applications like control of the work function of semiconductors,interface physics,field effect devices, molecular beam epitaxy, chemisorption and catalysis, corrosion, surface hardening etc.. The present volume is restricted to the so-called "clean" surfaces, i.e. to surfaces atomically clean and well characterized,leaving the more complex field of the contaminated surfaces and overlayers to a later occasion.
III/24D
Short: III/24D
Title: Physics of Solid Surfaces: Interaction of Radiation with Surfaces and Electron Tunneling
Author: Bradshaw, A.M.; Chiaradia, P.; Chiarotti, G.; Colella, R.; Hamers, R.J.; Hemmen, R.; Kellogg, G.L.; Ricken, D.; Schedel-Niedrig, Th.
Editor: Chiarotti, G.
Source: Landolt-Börnstein, New Series
Volume: III/24D
Year: 1996
ISBN: 3-540-56750-X
ISBN: 978-3-540-56750-9
Internet Resource: DOI:10.1007/b51875
RefComment: Hardcover
Abstract: In the last two decades surface physics has experienced an explosive expansion caused by the development and/or substantial improvement of surface sensitive techniques and UHV appa-ratus. It has grown into a mature field of research, with data of the highest accuracy and repro-ducibility. Surface physics is of great importance for technological applications like control of the work function of semiconductors,interface physics,field effect devices, molecular beam epitaxy, chemisorption and catalysis, corrosion, surface hardening etc.. The present volume is restricted to the so-called "clean" surfaces, i.e. to surfaces atomically clean and well characterized,leaving the more complex field of the contaminated surfaces and overlayers to a later occasion.
III/24a
Short: III/24a
Title: Physics of Solid Surfaces: Structure
Author: Chiarotti, G.; Fasolino, A.; Henzler, M.; Nicholas, J.F.; Ranke, W.; Selloni, A.; Shkrebtii, A.
Editor: Chiarotti, G.
Source: Landolt-Börnstein, New Series
Volume: III/24a
Year: 1993
ISBN: 3-540-56069-6
ISBN: 978-3-540-56069-2
Internet Resource: DOI:10.1007/b41604
RefComment: 148 figs., XI,362 pages. Hardcover
Abstract: In the last two decades surface physics has experienced an explosive expansion caused by the development and/or substantial improvement of surface sensitive techniques and UHV appa-ratus. It has grown into a mature field of research, with data of the highest accuracy and repro-ducibility. Surface physics is of great importance for technological applications like control of the work function of semiconductors,interface physics,field effect devices, molecular beam epitaxy, chemisorption and catalysis, corrosion, surface hardening etc.. The present volume is restricted to the so-called "clean" surfaces, i.e. to surfaces atomically clean and well characterized, leaving the more complex field of the contaminated surfaces and overlayers to a later occasion.
III/24b
Short: III/24b
Title: Physics of Solid Surfaces: Electronic and Vibrational Properties
Author: Calandra, C.; Chiarotti, G.; Gradmann, U.; Jacobi, K.; Manghi, F.; Maradudin, A.A.; Tong, S.Y.; Wallis, R.F.
Editor: Chiarotti, G.
Source: Landolt-Börnstein, New Series
Volume: III/24b
Year: 1994
ISBN: 3-540-56070-X
ISBN: 978-3-540-56070-8
Internet Resource: DOI:10.1007/b47750
RefComment: 709 figs., XII, 519 pages. Hardcover
Abstract: In the last two decades surface physics has experienced an explosive expansion caused by the development and/or substantial improvement of surface sensitive techniques and UHV appa-ratus. It has grown into a mature field of research, with data of the highest accuracy and repro-ducibility. Surface physics is of great importance for technological applications like control of the work function of semiconductors,interface physics,field effect devices, molecular beam epitaxy, chemisorption and catalysis, corrosion, surface hardening etc.. The present volume is restricted to the so-called "clean" surfaces, i.e. to surfaces atomically clean and well characterized,leaving the more complex field of the contaminated surfaces and overlayers to a later occasion.
III/27d
Short: III/27d
Title: Magnetic Properties of Non-Metallic Inorganic Compounds Based on Transition Elements: Oxy-Spinels
Author: Agostinelli, E.; Brabers, V.A.M.; Fiorani, D.; Testa, A.M.; Whall, T.E.
Editor: Wijn, H.P.J.
Source: Landolt-Börnstein, New Series
Volume: III/27d
Year: 1991
ISBN: 3-540-53877-1
ISBN: 978-3-540-53877-6
Internet Resource: DOI:10.1007/b41057
RefComment: 1030 figs., IX, 501 pages. Hardcover
Abstract: Volume III/27 covers the magnetic properties of inorganic compounds based on transition elements. It can therefore be considered as a supplement to volumes III/4 and III/12 Magnetic and other properties of magnetic oxides and related compounds, which appeared in 1970 and in the period 1978 - 1982 respectively. In a way, this volume also forms a counterpart to volume III/19, in which the magnetic properties of metals, alloys and metallic compounds are compiled. In the present subvolume III/27d oxidic compounds with the spinel structure are treated; they include both iron and non-iron oxy-spinels. Besides the magnetic data, physical and chemical properties which are of interest in connection with the magnetism of the spinels, have been given the necessary attention.
III/27g
Short: III/27g
Title: Magnetic Properties of Non-Metallic Inorganic Compounds Based on Transition Elements: Various Other Oxides
Author: Albanese, G.; Deriu, A.; Greedan, J.E.; Seehra, M.S.; Siratori, K.; Wijn, H.P.J.
Editor: Wijn, H.P.J.
Source: Landolt-Börnstein, New Series
Volume: III/27g
Year: 1992
ISBN: 3-540-55145-X
ISBN: 978-3-540-55145-4
Internet Resource: DOI:10.1007/b46090
RefComment: 408 figs.,IX, 238 pages. Hardcover
Abstract: Volume III/27 covers the magnetic properties of inorganic compounds based on transition elements. It can therefore be considered as a supplement to volumes III/4 and III/12 Magnetic and other properties of magnetic oxides and related compounds which appeared in 1970 and in the period 1978 - 1982 respectively. In a way this volume also forms a counterpart to volume III/19, in which the magnetic properties of metals, alloys and metallic compounds are compiled. The present subvolume III/27g covers binary oxides based on d-transition elements, oxides with trirutile and pyrochlore structure and oxides with a hexagonal crystal structure. The major part of the latter group is an updating of the compilations which appeared already in the Landolt-Börnstein subvolumes III/4b and III/12c. Physical and chemical properties which are of interest in connection with the magnetism of the oxides, have been given the necessary attention.
III/29a
Short: III/29a
Title: Low Frequency Properties of Dielectric Crystals: Second and Higher Order Elastic Constants
Author: Every, A.G.; McCurdy, A.K.
Editor: Nelson, D.F.
Source: Landolt-Börnstein, New Series
Volume: III/29a
Year: 1992
ISBN: 3-540-54410-0
ISBN: 978-3-540-54410-4
Internet Resource: DOI:10.1007/b44185
RefComment: 890 figs., XIV, 743 pages. Hardcover
Abstract: Some years after the publication of Vol. III/11 and its supplement III/18 dealing with elastic, piezoelectric, pyroelectric and optical properties of crystals, a complete recompilation of the data of these volumes and of new data was performed. Because of the growth of this subject matter it was found convenient to divide the material into four volumes, III/29a and b for the low frequency properties and III/30a and b for high frequency propertiesof dielectric crystals. The first subvolume III/29a contains exclusively second and higher order elastic constants including temperature and pressure coefficients.
III/33B1
Short: III/33B1
Title: Diffusion in Semiconductors and Non-Metallic Solids: Diffusion in Non-Metallic Solids (Part 1) without Volume Diffusion in Oxides
Author: Allen, C.E.; Beke, D.L.; Bénière, F.; Bruff, C.M.; Chadwick, A.V.; Erdélyi, G.; Faupel, F.; Hsieh, C.H.; Jain, H.; Kroll, G.; Matzke, H.; Murch, G.E.; Rondinella, V.V.; Seebauer, E.G.
Editor: Beke, D.L.
Source: Landolt-Börnstein, New Series
Volume: III/33B1
Year: 1999
ISBN: 3-540-62391-4
ISBN: 978-3-540-62391-5
Internet Resource: DOI:10.1007/b59654
RefComment: 424 figs., XVII, 574 pages. With CD-ROM. Hardcover
Abstract: This new volume of Landolt-Börnstein consits of two subvolumes. A on Diffusion in Semiconductors and B on Diffusion in Non-Metallic Solides. This separation was necessary, because the field and the number of data is too large to be compressed into a single volume only. This separation - we hope - also reflects the expected difference in the interets of potential users.
III/41D
Short: III/41D
Title: Semiconductors: Non-Tetrahedrally Bounded Binary Compounds II
Author: Kück, S.; Werheit, H.
Editor: Madelung, O.
Source: Landolt-Börnstein, New Series
Volume: III/41D
Year: 2000
Keyword: semiconductors
ISBN: 3-540-64966-2
ISBN: 978-3-540-64966-3
Internet Resource: DOI:10.1007/b71139
RefComment: 480 figs., XVII, 535 pages. Hardcover
Abstract: Vols. III/17a-i and III/22a, b (supplement) on semiconductor physics and technology have been published earlier, the latter covering new data on the technologically important group IV elements and III-V, II-VI and I-VII compounds only. The wealth of further data from the last decade is now being critically evaluated by over 30 well-known experts in the field of semiconductors. To meet the demands of todays scientists and to offer a complete overview on semiconductor data all data available so far are published in the following way: a series of five subvolumes covers only the supplementary data to volumes III/17 and 22.
III/4a
Short: III/4a
Title: Magnetic and Other Properties Of Oxides and Related Compounds
Author: Goodenough, J.B.; Gräper, W.; Holtzberg, F.; Huber, D.L.; Lefever, R.A.; Longo, J.M.; McGuire, T.R.; Methfessel, S.
Editor: Hellwege, K.-H.; Hellwege, A.M.
Source: Landolt-Börnstein, New Series
Volume: III/4a
Year: 1970
ISBN: 3-540-04898-7
ISBN: 978-3-540-04898-5
Internet Resource: DOI:10.1007/b19968
RefComment: 519 figs., XV, 367 pages. Hardcover
Abstract: Considered are magnetic, crystallographic, electric, optical, thermodynamic and further properties; while the magnetic, crystallographic and directly related data are compiled completely, the other properties are treated according to their importance. For a continuation and extension see below volume III/27
III/4b
Short: III/4b
Title: Magnetic and Other Properties Of Oxides and Related Compounds
Author: Bonnenberg, D.; Boyd, E.L.; Calhoun, B.A.; Folen, V.J.; Gräper, W.; Greifer, A.P.; Kriessman, C.J.; Lefever, R.A.; McGuire, T.R.; Paulus, M.; Stauss, G.H.; Vautier, R.; Wijn, H.P.J.
Editor: Hellwege, K.-H.; Hellwege, A.M.
Source: Landolt-Börnstein, New Series
Volume: III/4b
Year: 1970
ISBN: 3-540-05176-7
ISBN: 978-3-540-05176-3
Internet Resource: DOI:10.1007/b19969
RefComment: 1764 figs., XVI, 666 pages. Hardcover
Abstract: Considered are magnetic, crystallographic, electric, optical, thermodynamic and further properties; while the magnetic, crystallographic and directly related data are compiled completely, the other properties are treated according to their importance. For a continuation and extension see below volume III/27
III/7b1
Short: III/7b1
Title: Crystal Structure Data of Inorganic Compounds: Key Element : O
Author: Pies, W.; Weiss, A.
Editor: Hellwege, K.-H.; Hellwege, A.M.
Source: Landolt-Börnstein, New Series
Volume: III/7b1
Page: 1-674
Year: 1975
ISBN: 3-540-06919-4
ISBN: 978-3-540-06919-5
Internet Resource: DOI:10.1007/b19973
RefComment: 23 figs., XXIII, Hardcover
Abstract: Volume III/7 contains structure data on those compounds which contain at least one of the elements F, Cl, Br, I, O, N, and P and cannot be called "organic". The structure data of the remaining inorganic compounds and the elements are dealt with in volumes III/6 and III/14, while the organic compounds are treated in volumes III/5 and III/10. The systematic arrange-ment is based on the anions ordered according to "key elements", since this system allows the arrangement of the crystal structure data in such a way that both chemical and crystallographical relationships can be recognized. Structure data are compiled as completely as possible for all inorganic substances, where crystal structures have been examined by means of X-ray, neutron, and electron diffraction,and for which at least the lattice constants have been determined.
IV/19A4
Short: IV/19A4
Title: Thermodynamic Properties of Inorganic Materials: Pure Substances. Part 4: Compounds from HgH to ZnTe
Author: Scientific Group Thermodata Europe
Editor: Lehrstuhl für Theoretische Hüttenkunde, Rheinisch-Westfälische Technische Hochschule Aachen
Source: Landolt-Börnstein, New Series
Volume: IV/19A4
Year: 2001
Keyword: Heat Capacities; Enthalpies; Entropies; Gibbs Energies; Phase Transition Data
ISBN: 3-540-41025-2
ISBN: 978-3-540-41025-6
Internet Resource: DOI:10.1007/b71435
RefComment: 1660 figs., LVII, 415 pages, with CD-ROM, Hardcover
IV/4
Short: IV/4
Title: High-Pressure Properties of Matter
Author: Beggerow, G.
Editor: Schäfer, Kl.
Source: Landolt-Börnstein, New Series
Volume: IV/4
Year: 1980
ISBN: 3-540-09370-2
ISBN: 978-3-540-09370-1
Internet Resource: DOI:10.1007/b90280
RefComment: 589 figs., VIII, 427 pages. Hardcover
Abstract: The main topics are pressure dependences of phase equilibria, compressibility, thermal and caloric properties, transport phenomena, static and magnetic properties, optical phenomena, kinetic phenomena, and systems in the neighbourhood and above the critical area.
EINECS
Short: EINECS
Title: EINECS (European Inventory of Existing Commercial Chemical Substances)
Source: Official Journal of the European Communities
Volume: C 146 A (15.06.1990)
Page: 1
Year: 1990
Publish_Date: 1990/06/15

  File created on 2009/18/08 by LCI Publisher GmbH (Gaja Peters, Inga Thede, Volkmar Vill, Ron Zenczykowski)
  © 2009   Landolt Börnstein,   Springer-Verlag Berlin Heidelberg