An imaging plate containing photostimulable phosphor material, BaFBr:Eu2+, was found to be applicable to store images for nanosecond pulses as well as quasi-continuous radiations in 4 – 35 eV photon energy range. The sensitivity, which was defined as photostimulated luminescence intensity for a given incident photon number increased with the photon energy and had a peak at 6.2 eV. The intensity of the luminescence was confirmed to increase in proportion to incident photon numbers of the radiation. The readout system was improved and then pattern images were successfully restored. The resolution of imaging plate was found to be lower than 100 μm with our system, which depends on the intensity of a He-Ne laser for restoring images.

Single crystals of Ca3(Li,Nb,Ga)5O12 garnets have been grown from stoichiometric melts by micro-pulling down and Czochralski methods using Pt crucibles. It was found that the mixture of oxides with atomic ratio Ca : Li : Nb : Ga = 3 : 0.275 : 1.775 : 2.95 correspond to the garnet composition which melts congruenlly at about 1450°C. Solid state reaction data of the compounds related with this material are also reported. Lattice parameter of all Ca3(Li,Nb,Ga)5O12 crystals grown was about 1.254 nm. Transparent and bubble-free crystals of Ca3LixNb1.5+xGa(3.5+x)Ga(3.5−2x)O12 (x = 0.25 and 0.275) were grown by Czochralski technique in air. An optical transmission spectrum of the crystals was studied. No absorption was detected in 400–1200 nm wavelength range.

Structural studies, electrical resistivity, and Seebeck coefficient measurements are reported in the range 4.2 − 300 K for single crystals of NiS2−xSex (0 ≤ x ≤ 0.71) grown from a Te melt. Over the entire temperature and composition ranges there are no large scale structural changes concomitant to a variety of magnetic ordering phenomena, and to a changeover from insulating to metallic characteristics as x increases. Thus, the evolution in transport characteristics with x can be studied without interference from the lattice; moreover, the electron count is unaffected by substitution of Se for S. The existence of anomalous peaks in resistivity as a function of temperature is attributed to significant electron correlation phenomena which allow the entropy of charge carrier to play a dominant role. The complex temperature dependence of the Seebeck coefficient is attributed to the participation of both electrons and holes in charge transport.

A new type of lanthanide transition metal pnictide-oxide, Ln3Cu4P4O2 (for Ln = La, Ce, and Nd), is reported. The crystal structure is made from Ln2O2 layers of the Pb2O2 type stacked with layers of Cu2P2 tetrahedra. The existence of a homologous series of compounds with similar chemistry connecting the BiCuOSe and ThCr2Si2 structure types is indicated. The resistivity of La3Cu4P4O2 is metallic, with no superconductivity observed above 2K. The Ce and Nd compounds have magnetic susceptibilities characteristic of the trivalent Lanthanides. The Ce compound orders magnetically at approximately 0.8 K.

Layered copper-oxide superconductors exhibit the highest critical transition temperatures of any materials. Yet all of the known double perovskites A′A″B′B″O6 containing copper have a random or rock salt distribution of the B cations with the exception of the unique layered arrangement found in La2CuSnO6. Only the layered arrangement contains the CuO22- planes which are necessary for high-temperature superconductivity. The occurrence of layered or two dimensional structures increases markedly when vacancies are introduced on the oxygen sublattice, as evidenced in Ln2AEmCu2TimO5+3m (Ln = lanthanide, Y: AE = Ba, Ca: 2 ≤ m ≤ 4). Similarities among oxygen-deficient structures, especially those with two-dimensional solid-state features, are discussed. Combined conductivity and thermopower analysis are presented to elucidate their unique internal chemistry, defect structure, and conduction parameters. In particular, data for La2-xSrxCuSnO6 are presented and related to the crystal chemistry of the copper-oxygen layer. These data are compared with La2Ba2Cu2Sn2O11 and La2Ba2Cu2Ti2O11 to illustrate the significance of oxygen vacancies on the properties of the copper oxygen planes. New layered cuprates are discussed including the mixed A-site stoichiometries Ln′Ln″AEmCu2TimO5+3m (Ln = lanthanide, Y: AE = Ba, Ca: 2 ≤ m ≤ 4) which contain the smaller lanthanide (Ln″) ordered between the closely spaced, facing sheets of Cu-O square pyramids.

Contrary to the commonly accepted model, we conclude that the zinc interstitials in Zn1+xO are not ionized. Instead, the electron pair associated with the interstitial zinc is trapped in a metal—metal bond. The increase in conductivity on initial reduction of zinc oxide is associated with impurities such as silicon which are compensated by extra oxygen unless removed by reduction. Zinc oxide powders and thin films were prepared with the dopants B, Al, Ga, In, and Ge. By using high temperatures and highly reducing conditions, conductivities 1000 times higher than previously reported for powders were obtained for some of our powders.

The crystallography and electronic properties of the Ln2-xSr1+xMn2O7 manganese oxides adopting the n = 2 Ruddlesden-Popper (RP) structure are discussed, focusing on the structural phase diagrams and electronic properties in the vicinity of the Mn +3.5 oxidation state and in particular the ease of synthesis of single phases of these materials.

The critical magnetic properties of bulk La0.67Ca0.3MnO3 and magnetoresistance of a thin film with the same Tc were measured and critical exponents determined. The magnetization data can be scaled with β = 0.3 and γ = 0.9, except above Tc which appears to be affected by a region where X3 (M = XH + X3H3) is positive. An M2 dependence of the magnetoconducitvity is observed above Tc. Below Tc, however, such a correspondence between the critical magnetic and transport behavior is not found.

Neutron powder diffraction studies of the layered compounds R1.2Sr1.8Mn2O7, (R = La,Pr, Nd), RSr2Mn2O7 (R = Pr,Nd),and La1.4Sr1.6Mn2O7 show that the degree of distortion of the MnO6 octahcdra do not correlate with the appearance of a metal-insulator (MI) transition in these compounds. Instead, the in-plane Mn-O bond length appears to be a better indicator of the electronic behavior. Detailed bulk magnetization studies on single crystal La1.2Sr1.8Mn2O7 show thai there are three magnetic regimes as a function of temperature: paramagnetic insulator, short-range ordered (SRO) fcrrromangct, and long-range ordered (LRO) fcrromagnct. Scaling analysis indicates that a 2D finite-size XY model is an appropriate description of the magnetic state in the SRO regime.

Magnetic, transport, and structural data on polycrystalline samples of the system La1-xSrxTiO3, 0 ≤ x ≤ 0.8, show an abrupt, but apparently smooth, transition from p-type polaronic conduction in a canted-spin antiferromagnetic system for x ≤ 0.04 to metallic, mass-enhanced Pauli paramagnetic behavior for x ≥ 0.1 with evidence for a spin glass and a discontinuous drop in TN in the transition range. We interpret these results as a manifestation of the coexistence of two distinguishable electronic domains within a single crystallographic phase as a result of cooperative displacements of the oxygen atoms.

We have studied the effect of hole doping via Li substitution in La2CuO4 and La2NiO4. The response to hole doping of the Ni (S=1) sublattice is distinct from that of the Cu (S=1/2) sublattice. These effects are seen most clearly for La2Cu0.5Li0.5O4 and La2Ni0.5Li0.5O4 in which the Li ions form an ordered superlattice. It appears that Ni is in a low-spin d7 configuration whereas Cu is in a d9-ligand “Zhang-Rice” configuration. Despite this difference, the response of both La2CuO4 and La2NiO4 to hole doping is surprisingly independent of whether Sr (which substitutes out of plane for La) or Li (which substitutes in the plane for Cu/Ni) is used as the dopant.

Polycrystalline samples of A1–xA'xNbO3 (A=Na+, K+; A'= La3+, Sr2+) were prepared by solid-state reactions and the relationship between the structure and electrical properties was examined. Single-phase products were obtained for Na1–xLaxNbO3 (x ≤0.1), K1–xLaxNbO3 (x ≤0.15), Na1–xSrxNbO3 (x ≤0.3), and K1–xSrxNbO3 (x ≤0.5). The structures of the sodium-containing compounds and potassium-containing compounds were indexed according to a pseudocubic and cubic symmetry, respectively. The resistivity measurements showed semiconductive behavior for the lanthanum-containing samples. The strontium-containing samples showed semiconducting properties for x ≤0.2, while a transition to metallic conduction at low temperature was observed for x >0.2.

The crystallographic similarity between the Ir3Ge7 (D8f) and γ-brass (Cu5Zn8, D82) structures is discussed. By considering all phases known to possess the Ir3Ge7 structure, it is shown that phases of this structure type obey essentially the same electron concentration rules as does γ-brass, possessing on average 22 atoms/formula unit. Based on crystal-chemical considerations, it is further suggested that the Ir3Ge7 structure may be considered to be a structural derivative of γ-brass, in which 12 atoms have dropped out of the γ-brass lattice and the remaining atoms have undergone a certain amount of rearrangement in order to accommodate such a large concentration of vacancies. Finally, as further support of this idea, the phase NiGa4 is presented as an example of another γ-brass derived structure which contains crystallographic features of both γ-brass and the Ir3Ge7 structure.

PtGa2 has previously been reported to exist as both a brass-colored, fluorite-structured phase and as a silver-colored alloy of unknown crystal structure. The crystal structure of the silver-colored form is reported here, along with a discussion of the stoichiometric factors responsible for the polymorphy of this phase. The silver-colored form belongs to the space group 141/acd, with the lattice parameters a = 8.5544(4) and c = 21.574(17) Å, and Z = 32. The structure consists of layers of Pt and Ga stacked along the c axis, in which two crystallographically different Pt and Ga atoms have similar environments involving eight and nine nearest neighbors, respectively. This structural arrangement may be the prototype for a family of ternary platinum metal-Group B-based phases. The present investigation also necessitates changes in the currently accepted Ga-Pt phase diagram. Stoichiometric PtGa2 undergoes a structural transformation upon cooling from a brass-colored fluorite structure to this silver-colored, tetragonal structure. However, the transformation is inhibited if the composition of the fluorite-structured phase is Ga-poor.

The one-dimensional compounds Sr3MgPtO6, Sr3MgIrO6, Sr3MgRhO6, Sr3GdRhO6, have been synthesized and structurally characterized by Rietveld refinement of powder X-ray diffraction data. All four compounds are isostructural with the rhombohedral K4CdCl6-type structure. The structure consists of infinite one-dimensional chains of alternating face-shared MO6 octahedra (M = Pt, Ir, Rh) and M′O6 (M′ = Gd, Mg) trigonal prisms. The strontium cations are located in a distorted square antiprismatic environment. Magnetic susceptibility data show that both Sr3MgIrO6 and Sr3MgRhO6 obey the Curie-Weiss law with θ = −6(1) K, and θ= −15(3)K, respectively. Sr3GdRhO6 obeys the Curie law with μeff = 7.80 B.M, consistent with an oxidation state of +3 for both rhodium and gadolinium.

Results of iron-5 7 Mössbauer spectroscopy and ac and dc susceptibility study of the double perovskite phases, CaFeTi2O6 (A) and CaFe3Ti4O12 (B) are presented. Both phases exhibit spectral broadening effects with decreasing temperature and incipient magnetic hyperfine splitting attributable to novel slow paramagnetic relaxation at the tetrahedral and square planar sites of (A) and the square planar sites of (B). The temperature dependence of magnetic moment for (A) corresponds to classical single ion zero field splitting, while that of (B) indicates antiferromagnetic exchange interactions. There is no evidence of cooperative long range magnetic order in these materials.

Effects of non-stoichiometry on anisotropie magnetic states in CuFeO2 with a so-called delafosite structure have been investigated using CuFeO2+δ (δ=-0.061, -0.026, 0.014, 0.085) single crystals. Each single crystal is grown using the floating zone method in each controlled atmosphere and found to have good quality. All crystals show two anisotropie successive antiferromagnetic transitions in the temperature dependence of magnetic susceptibilities. The higher antiferromagnetic transition temperature is not affected by the non-stoichiometry. On the other hand, the lower one shows distinct effects of the non-stoichiometry, depending on the kind of oxygen defects. Oxygen deficiency leads to an increase in TN2, while excess oxygen leads to a decrease. It is also found that all samples show clear anisotropie step anomalies in the magnetization curve up to 38 T and that the anomalies and hystereses depend on the nonstoichiometry.

Powder samples of the anhydrous compounds M2+(ReO4)2 (M = Mn, Fe, Co, Ni, and Cu) were prepared. All have trigonal symmetry, except M = Cu which is Jahn-Teller distorted to monoclinic symmetry, I2/m. Single crystals of the Fe and Cu compounds were grown by vapor transport and their layered structures determined. Ferromagnetism, deduced from ac susceptibility and dc magnetization studies, is exhibited by the Fe (TCurie = 8.5 K), Co (TCurie = 4.7 K), and Ni (TCurie = 12.5 K) phases. They show 2-D ferromagnetic (intralayer) interactions as well as a 3-D ferromagnetic (interlayer) ground state with both of these effects obvious in the heat capacity of Ni(ReO4)2. Low-temperature powder neutron diffraction confirms the ferromagnetism of Ni(ReO4)2 below 12 K, and also reveals a structural phase transition occurring between room temperature and 77 K. The origin of the 3-D ferromagnetic ground states of the Fe, Co, and Ni perrhenates is the result of dipolar interlay er interactions, as opposed to superexchange between the layers. Susceptibility results of the Cu perrhenate indicate intralayer ferromagnetism and any long-range 3-D order occurring at T ≤ 1.5 K. The Mn compound is antiferromagnetic.

Aspects of the low temperature magnetism of some distorted cryolite-like compounds of high-spin iron III, namely Na3[FeF6], [NH4]3[FeF6] are presented. The behavior of these systems is compared to iron-57 Mössbauer spectroscopy and ac-susceptibility results for the related [Co(NH3)6][FeF6] and the modified pyrochlore [NH4CoFeF6] obtained via thermolysis of [Co(NH3)6][FeF6] under nitrogen.

A clamp-type hydrostatic pressure device for the measurement of properties of perovskite-related compounds under pressure was established in our laboratory and applied to the measurements of resistivity, AC susceptibility, Hall effect and ionic conductivity. In usual perovskite-type oxides, loading of a pressure of 1 GPa (lOkbar) corresponds to a contraction of interionic distance as large as 0.2%. This small value is not enough to evaluate the whole scheme of phase transition behavior for perovskite-type oxides but very effective for the observation of changes in interactions between electrons and ions. Some problems concerned with this method have been pointed out.