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Synthetic single crystal diamonds are irradiated with 100 MeV carbon-ion and characterized by measurements of the X-ray lattice parameter and diffuse scattering (XDS) at room temperature. The lattice parameter increases with the ion fluence. The intensity of XDS diffuses asymmetrically to form a streak along the [-1 0 0] direction parallel to the reciprocal lattice vector. These results suggest that interstitial atoms induced by irradiation aggregate to form dislocation loop on the (1 0 0) plane in the synthetic single crystal diamonds. The results are similar to the XDS of boron-doped single crystal diamond suggesting that boron atoms are likely to form precipitates on the (1 0 0) plane. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Natural and synthetic single crystal diamonds (types Ia, Ib, IIa and IIb) have been characterized by measurements of the X-ray integrated scattering intensity, lattice parameter and diffuse scattering. We found a drastic increase of X-ray integrated scattering intensity for natural and B-doped diamond crystals. Synthetic type IIa diamond was also measured for comparison. Measurements of the lattice parameters have been made at room temperature by using the X-ray bond method. We found that the lattice parameter is smallest for natural diamond and largest for the B-doped diamond. Diffuse scattering experiments were performed using a four circle diffractometer at room temperature. We measured the diffuse scattering for (4 0 0) Bragg reflection for the four types of crystals. The scattering intensity of the natural crystals diffuses asymmetrically to form a streak along the [1 0 0] direction parallel to the reciprocal lattice vector. These results suggest the existence of the nitrogen atom platelets on (1 0 0) plane in the natural diamond. We also found the diffuse streaks along the [ 1 ˙ 0 0 ] direction for (4 0 0) Bragg reflection for the B-doped crystal, suggesting that boron atoms are likely to form precipitates on the (1 0 0) plane.

We report electrical transport measurements of synthetic diamonds doped with boron about 100 ppm. The resistivity has been measured in the temperature range 20--300 K by the van der Pauw method. We have also investigated infrared absorption coefficient at room temperature. Furthermore, we have studied the effect of ${\mathrm{P}}^{+9}$ ion irradiations with 150 MeV which introduce donor defects and also the influence of the annealing after the irradiation. The key features of the present measurement are as follows: (i) The observed temperature dependence of resistivity shows characteristic features of the variable-range-hopping (VRH). A crossover from ${T}^{\ensuremath{-}1/4}$ behavior of Mott VRH to the ${T}^{\ensuremath{-}1/2}$ form of Efros VRH is found to occur at 100 K. (ii) Below 50 K we have observed the hard gap ${T}^{\ensuremath{-}1}$ form. The width of the hard gap is about 10 meV. (iii) The experimental results are quantitatively explained by the theory of VRH. (iv) The observed width of the optical hard gap is equal to that of the hard gap obtained from resistivity. (v) The annealing effects appear only in the hard gap region and do not appear in the variable-range-hopping region. This result leads to the speculation that the hard gap is weakened by the lattice defects.

The lattice parameter of a single-crystal boron-doped synthetic diamond has been measured in the range 4.2-300 K by x-ray diffraction (Bond method), with precision . Over the whole range the results are consistent with A, where T is the absolute temperature. The dilation due to doping indicates a boron concentration of about 100 ppm. The increase of thermal expansion over that of an undoped synthetic diamond is found to be unexpectedly large (10-15%), giving an apparent dilation on doping that is markedly temperature dependent.

X-ray diffuse scattering was measured for quenched copper. The diffuse scattering near the (111) and (222) reflections was observed at room temperature for as quenched and successively annealed samples from 200 to 800°C. A sharp and strong subpeak accompanied by a thermal diffuse scattering was appeared on a smaller angle side of the (111) Bragg angle. The subpeak was disappeared after annealing at 400°C. A characteristic feature of this scattering is from vacancy type dislocation loops, of which the mean radius is estimated to be about 1 nm, associated with a caustic scattering.

The effect of high energy B-ion beam irradiation on the soft magnetic properties of Fe-based amorphous ferromagnetic alloys, FeCuNbSiB and FeBSiC, has been investigated by measuring hysteresis loops. The improvement of soft magnetic properties is found to be better than in the case of high energy P-ion irradiation. The increase of permeability at the initial stage of B-ion irradiation in FeCuNbSiB amorphous alloy was significant.

Measurements of lattice parameters were made for a single crystal of a high-purity synthetic diamond using the x-ray-diffraction Bond method between 4.2 and 300 K. The key features of the present measurement are as follows: (1) The lattice parameter is determined with an accuracy of ${10}^{\ensuremath{-}6}.$ (2) A very small negative thermal expansion is detected between 30 and 90 K. (3) Thermal expansion shows a behavior of the ${T}^{4}$ law represented by the Debye theory within the measuring temperature range. By comparing the present results with the previously reported results for nitrogen-doped diamond and boron-doped diamond, it is found that diamond becomes harder following doping by nitrogen.

Synthetic single crystal diamonds were irradiated with 100 MeV carbon ions up to a fluence of 3.6×10 15 ions/cm 2 at about 100 K and with 3 MeV electrons up to 1×10 19 e/cm 2 at 60°C. Volume changes after irradiation were studied by means of lattice parameter measurements by X-ray diffraction, indicating linear increases of the lattice parameter with fluence. A drastic increase of the integrated intensity of the scattered X-ray was observed after ion irradiation, and a large increase after electron irradiation. The drastic change is due to the so-called “disappearance of the extinction effects” in the dynamical diffraction theory, which is associated with the introduction of defects by the irradiation. The integrated scattering intensity in diamond is very sensitive to the amount of defects produced by the irradiation.

Amorphous ferromagnetic alloy, Fe-Cu-Nb-Si-B and Fe-B-Si-C were irradiated with high energy ion beams, and the differences in the magnetic properties before and after the irradiation were investigated by measuring low field magnetic hysteresis loops. It was found that in the early stage of the irradiation the soft magnetic properties improved. After a long irradiation, however, they deteriorated.

Precision lattice parameter in La1.85Sr0.15CuO4 single crystal superconductor has been measured in a wide temperature range between 4.2 K and room temperature by the X-ray Bond’s method. An anomalous lattice contraction associated with the appearance of the superconductivity was found in c-plane. Along c-direction, on the contrary, an anomalous expansion of the lattice was observed. The relative spontaneous change in the lattice parameter in c-plane was 2.3xl0­-5 and that of c-axis was 1.5×l0-5 at 4.2 K. The temperature dependence of the spontaneous lattice change was compared with currently existing theories for high Tc superconductivity.

Weak-field Hall coefficient R H has been measured in the temperature range from 4K to 300K for Nd1.85Ce0.15isCuO4−δ c-axis oriented thin films having various oxygen deficiencies incorporated by the successive reduction treatment method. This method enables us to observe a systematic change in R H and its temperature T dependence, which otherwise is difficult to obtain due to scatter both in the oxygen content and Ce concentration. It is found that for a Nd1.85Ceo0.15CuO4−δ films annealed in oxygen, the resistivity ρ shows a semiconductive T dependence at low temperatures without indication of the superconducting transition, R H is negative and exhibits semiconductive T dependence. As the oxygen content is successively decreased, the ρ and R H decrease and the T dependence starts to exhibit metallic behavior. These changes are accompanied by a superconducitng transition around 20K. With further reduction, R H changes the sign from the negative to positive, while ρ remains to exhibit metallic T dependence with depressed T c . Still further reduction results in an insulatingly high ρ value. The results imply that R H is a, sensitive function of oxygen content, namely, the electron carrier density.

The magnetization process has been studied in amorphous Fe73.5Cu1Nb3Si13.5B9 alloy before and after fine crystallization by using a very low frequency vibrating sample magnetometer over a wide range of external magnetic field up to 1.8 T. It was found that the H−12; term decreases largely after the heat treatment, while the change in the H-1 term was rather small. This fact means that the number of point-like defects was decreased by the heat treatment rather than a change occuring in quasidislocation dipoles.

Lattice parameter measurements have been made in a La1.85Sr0.15CuO4 single crystal superconductor between 4.2 K and room temperature by the X-ray Bond method. A structural distortion near the superconducting transition temperature of 33 K has been observed. The lattice spacing in the c-direction increases below the superconducting transition temperature with decreasing temperature. The change in the lattice parameter, Δc/c0, between 4.2 K and 33 K, is 2×10−5. Along a direction perpendicular to the c-axis, on other hand, the lattice spacing decreases more rapidly than expected from normal thermal contraction. The possible importance of these results for existing theories of high temperature superconductivity is noted.

The reflow of borophosphosilicate glass (BPSG) was studied by the rapid heating technique in two step irradiations using a halogen lamp. Pre-annealing (800° C, 30 s) during the first step irradiation, which aims to reduce the heating delay for the BPSG film, was carried out prior to high temperature heating (1050–1200° C, 20 s). The reflow angle with pre-annealing is consistently smaller than that without pre-annealing. Moreover, the reflow difference between with pre-annealing and without pre annealing decreases with increasing temperature because the heating delay for the BPSG film increases. The heating delay is primarily caused by thermal resistance between the film and the silicon wafer because, as the result obtained from the finite element method indicated, the heat conduction delay between the film surfaces was negligibly small. The equation for heat resistance can be solved analytically and the thermal resistance coefficient can be estimated by this solution, using the physical parameters of the film and the experimental results.

The lattice parameter of synthetic diamond single crystals has been measured in the range 4.2-320 K by the X-ray diffraction method. The lattice parameter is found to be nearly constant between 4.2 and 90 K. The thermal expansion coefficient α calculated from the experimental results is very small (of the order of 10-7 or less) and no definite evidence of the negative thermal expansion is found within our relative experimental accuracy of the order of ±1×10-6.

Reliable dependences of negative longitudinal magnetoresistance (NLM) for n-type InSb on carrier concentration n and on mobility ? are investigated at 77 K up to 1.8 T with a number of specimens, whose n range from 5?1013 cm-3 to 4?1017 cm-3 and ? from 7?105 cm2/V?s to 4?104 cm2/V?s. The maximum NLM, ?// (1.8 T)/?0?0.5, occurs at n?3?1015 cm-3 and correspondingly at ??2?105 cm2/V?s just before the occurrence of carrier degeneracy (n=4?1015 cm-3 at 77 K) in accordance with existing theories. NLM disappears with increasing n because of degeneracy, while it becomes less negative with decreasing n due to decreasing ionized impurity scattering and crystal inhomogeneity. The disappearance of NLM at n

The thermal expansion of the lattice constant of a GaP crystal was measured in the range 4.2-300K using the Bond method. The authors found a negative thermal expansion coefficient for GaP at low temperatures. They also calculated the Gruneisen parameter and this was negative below 50K. These experimental results do not agree with the phenomenological theory in which a positive thermal expansion coefficient for GaP is predicted at low temperatures.

The thermal expansion of the lattice constant of InP crystal has been measured in the range 4.2-300 K by the Bond method and the results are shown graphically. The thermal expansion coefficient alpha calculated from the experimental results is negative between 15 and 80 K and positive below 15 K. The corresponding Gruneisen parameter gamma closely follows the behaviour of alpha and the values of alpha and gamma are tabulated and shown graphically. The results do not agree with the phenomenological theory in which only a negative alpha is predicted for InP at low temperatures.

Magnetoresistance and transverse magnetophonon resonance data at 77 K for n-type InSb crystals (prepared by the method described in Part I) are given, with the aim of detecting residual impurities and inhomogeneities. The importance of 1) using boat material not wetted by InSb and 2) low-temperature annealing (at 200°C for one week) are shown experimentally. The concentration of residual impurities is estimated to be 2×1014/cm3, and three kinds of impurity are found. Furthermore, dislocations and non-uniform distribution of the compensating acceptor impurities are identified as the source of inhomogeneities. It is concluded that the carrier concentration of less than 1014/cm3 is due to the compensation effect and that the reliable maximum mobility at 77 K is 8×105cm2/V·s.