ISSN:0370-1972    

DOI:10.1002/pssb.2221810133

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

ISSN:0370-1972    

DOI:10.1002/pssb.2221810134

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe phase transitions in [Mg(H2O)6]GeF6are investigated with an Mn2+EPR probe substituted for Mg2+ions in the lattice. An axial symmetry phase with space group R3is observed above 403 K. The ferroelastic phase transition at 318 K is of first order and leads to monoclinic symmetry and to the development of a domain structure. In the intermediate phase the spectra exhibit anomalous changes of the lineshapes resulting from incommensurate modulation of the crystal field fine structure tensor. The results of EPR studies are interpreted both in terms of the plane‐wave and multi‐soliton mod

ISSN:0370-1972    

DOI:10.1002/pssb.2221810105

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractA thermodynamic analysis of the Anderson parameter is found to yield useful relations for estimating the temperature dependence of interatomic separationsr(T) and thermal expansion coefficient α(T). The relations can be used to predictr(T) and α(T) up to the melting temperatures of solids. The results obtained for sixteen alkali halides are compared with the available data reported in the literature. The values ofr(T) are in close agreement with the data based on the theory of interionic potentials. The variation of the thermal expansion coefficient is discussed in the light of other investigation

ISSN:0370-1972    

DOI:10.1002/pssb.2221810106

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe influence of hydrostatic pressure on the temperature dependences of transverse USW velocities is studied in the region of phase transitions and of triple points of {N(CH3)4}2CuBr4crystals. The pressure‐temperature phase diagram is obtained. The linear electroacoustic effect is detected only in the region of the ferroelectric phase. The anomalies of acoustic and electroacoustic properties are considered within the framework of a phenomenological theor

ISSN:0370-1972    

DOI:10.1002/pssb.2221810107

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractSince its discovery, the SrTiO3: Ca system is known to exhibit a number of features which were thought to arise from an impurity induced disorder. Non‐linear dielectric measurements are used to obtain a more quantitative insight into this disorder. For 0.001

ISSN:0370-1972    

DOI:10.1002/pssb.2221810108

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe relationship between two anharmonic physical properties is considered: the bulk‐modulus temperature dependence (1/B) (∂B/∂T) and the thermal expansivity (1/V) (∂V/∂T). For the first, Varshni's relationship is used, which derives from an Einstein‐oscillator model of crystals. For the second, a relationship from Slater is used with a similar basis. The ratio of the two properties is found to be γ + 1, where γ denotes the usual Gröneisen parameter, Varshni's adjustable parametersis interpreted in terms of the Gröneisen parameter, the Einstein temperature, and the atomic volume. Applied to metals, our relationship works well for those with s‐p‐electron bonding, but poorly for those where d‐electrons

ISSN:0370-1972    

DOI:10.1002/pssb.2221810109

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe results of investigation of GaAs single crystals heavily doped by group VI elements are considered. The doping effects are studied by methods of free carrier infrared absorption, photoluminescence, ultrasonic, and calorimetric methods. For the explanation of the observed peculiarities in doped gallium arsenide the thermodynamic model of phase transitions is proposed using the properties of complex formation in this semiconducting compound.

ISSN:0370-1972    

DOI:10.1002/pssb.2221810110

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractElectron movement in a spatially periodic high‐frequency electric field is considered. If the spatial period is small enough and the frequency is sufficiently high, the effect of this field on the charge particle is in a sense equivalent to the effect of a time‐independent effective potential that is a sequence of deep ‘dynamic’ quantum wells where the electrons are confined. The physical model is proposed which could be described in terms of such a Hamiltonian. Also the influence of an external quantizing magnetic field on such quantum well is considered and the existence of a quantum dot in this system is demon

ISSN:0370-1972    

DOI:10.1002/pssb.2221810111

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractCurrent‐voltage (I‐V) characteristics of short‐period (≦2.0 nm) amorphous Si/SiO2quantum structures (QWs) are investigated with a scanning tunneling microscope (STM). The tunneling current regime has been realized so that the applied bias is dropped mainly across the tip‐sample contact and the nondistorted energy structure of the QW conduction band is probed by tunneling electrons. Such measurements give the possibility to obtain energy positions of QW subbands without additional assumptions about the voltage drop across the layers. TheI‐Vcurves observed are described taking into account sequential resonant tunneling. In the flow current regime the negative differential resistance caused by alignment of ground and first excited electron states is observed even at room temperature due to the high barrier in a

ISSN:0370-1972    

DOI:10.1002/pssb.2221810112

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY