摘要:

This paper describes the formation of chalcogenide glasses with high contents of heavy metals and some of their properties. In the systems HgSe‐GeSe‐GeSe2, HgTe‐GeSe‐GeSe2and HgTe‐GeTe‐GeSe2glasses up to 25 mole % Hg can be prepared on conventional cooling technique from the melt. HgSe‐GeSe melts yield also glasses are formed up to 22 mole % Pb. Ge‐Sn‐Se‐Te glasses were investigated in series substituting the homologous elements by each other. Conclusions on the structure are drawn from measurements of the density, thermal, optical and electric properties.

ISSN:0094-243X    

DOI:10.1063/1.30773

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Optical absorption measurements have been made on BaTiO3thin films prepared by rf sputter deposition. An amorphous and a distinct microcrystalline phase have been studied in addition to the normal crystalline phase. A sharp absorption threshold is obtained at 3.6, 3.95 and 4.3 eV for the crystalline, microcrystalline, and amorphous phases, respectively. The increase in gap correlates with an increasing lattice parameter.

ISSN:0094-243X    

DOI:10.1063/1.30775

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We compare optical homogeneous linewidth measurements for the resonant5D0−7F0transition of Eu3+in glasses and crystals. The linewidth in the amorphous hosts is significantly larger than in crystals with similar coordination, and shows an unusual temperature dependence which cannot be explained by the normal ion‐phonon relaxation mechanisms. This behavior probably arises from an interaction between the impurity ion and low energy ’’disorder modes’’ in the glasses. Possible models are discussed, consistent with recent NMR and ultrasonic attenuation experiments. In addition, excitation scans have been taken in search of discrete sites for the rare earth impurity in the glassy host. No such sites can be detected with a 1GHz resolution.

ISSN:0094-243X    

DOI:10.1063/1.30776

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A five‐member ring dominated, tetrahedrally bonded continuous random network model of 940 atoms was constructed. The density and radial distribution function (RDF) of the model were calculated from the measured coordinates of the atoms. The RDF is in agreement with published results on amorphous germanium. Structural anisotropy of the model was noted visually by rotating the model through various orientations. This anisotropy was confirmed with the calculated intensities of scattered x‐rays.

ISSN:0094-243X    

DOI:10.1063/1.30777

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Atomic arrangements in amorphous metals and alloys are discussed in terms of continous dense random packing model structures. Constraints which may be introduced into computer generated hard sphere packings to insure tetrahedron perfection are described. The agreement between experiment and computer generated binary dense‐random‐packing‐of‐hard‐spheres models which emphasise nearest neighbor tetrahedral ordering is encouraging. Such models reproduce the observed, composition dependent structural features seen in the radial distribution functions of amorphous rare each metal − transition metal alloys.

ISSN:0094-243X    

DOI:10.1063/1.30778

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Amorphous phases of Mo and Nb which are stable at room temperature have been obtained by e‐beam vapor deposition of the metals in a partialN2atmosphere on substrates kept below 100K. The structure of these films can be described in terms of the DRPHS model. The amorphous Mo‐films show a large increase in the superconducting transition temperature (compared to bulk Mo) whileTof amorphous Nb films decreases. For the most homogeneous Mo1−xNxfilms theTcobtained is near 8.5K and the transition width is ≲0.1K. In the absence of a nitrogen atmosphere pure Mo‐films, vapor quenched onto sputter cleaned substrates at 4.2°K are found to be crystalline bcc. Contamination appears to stabilize amorphous or other nonequilibrium crystalline phases (fcc, hcp).

ISSN:0094-243X    

DOI:10.1063/1.30779

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The spontaneous magnetizationsM(T) of the ferromagnetic glasses (Fe40P14B6, Fe75P15C10and Fe80P16C3B1) have been measured by57Fe Mo¨ssbauer spectroscopy. At low temperatures, the change ofM(T) varies as B3/2(T/Tc)3/2, characteristic of ferromagnetic spin waves with an anomalously large value of B3/2. ForTclose toTc,M(T) varies as a power law with critical exponent &bgr; close to 1/3.

ISSN:0094-243X    

DOI:10.1063/1.30780

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We study thedelectronic density of states of pure amorphous transition metals. We show, by calculation on small clusters and on infinite systems, that the icosahedral structure enhances the density of states in the middle of the band and so diminishes the cohesive energy. Calculation of the density of states for a non degeneratedband hamiltonian emphasizes the importance of a correct treatment of the local order.

ISSN:0094-243X    

DOI:10.1063/1.30781

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The electronic states in liquid Cu are calculated within the framework of the muffin tin model. Results for both the complex energy bands and the average density of states are presented and discussed.

ISSN:0094-243X    

DOI:10.1063/1.30782

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

57Fe hyperfine spectra have been measured in several bulk amorphous rare earth‐iron (RE‐FE) alloys including DyFe2, GdFe2and SmFe2. GdFe2and SmFe2have magnetic ordering temperatures (Tc) above room temperature whereas for DyFe2,Tc=229 ±3°K. DyFe2, which has large local anisotropy associated with the rare‐earth orbital angular momentum, displays broad asymmetrical hyperfine patterns. GdFe2which has weak local anisotropy, has a broad symmetrical pattern and a much higherTc. The asymmetrical hyperfine patters are interpreted in terms of averages over the randomly distributed quadrupolar and pseudo‐dipolar hyperfine field directions. The average hyperfine fields at low temperature are found to scale, for the most part, with the spin (g−1)J of the rare earth. However, the average fields measured in this study are markedly lower for the lighter rare earths than observed in previous Mo¨ssbauer studies of thin‐film ’’amorphous’’ alloys. A dramatic reduction of the recoil‐free fraction is observed to occur as the temperature is lowered belowTcin DyFe2.

ISSN:0094-243X    

DOI:10.1063/1.30784

出版商:AIP    

年代:1976

数据来源: AIP