Влияние состава зародышевого слоя AlGaAs на формирование антифазных доменов в структурах (Al)GaAs, выращенных газофазной эпитаксией на подложках Ge/Si(100)

GaAs-based heterostructures grown by metalorganic vapor-phase epitaxy on virtual Ge/Si substrates using an AlxGa1-xAs seed layer with different aluminum content x in the solid solution are investigated. The effect of solid solution composition on the density and size of antiphase domains emerging on the sample surface and on the optical properties of the GaAs layer is shown. Si(100) substrates with a small unintentional miscut of 0.7° to [110] were used for growth.

The impact of solid-solution composition on kinetics and mechanism of [2+2] photodimerizations of cinnamic acid derivatives

We propose the use of solid-solutions for the modulation of the kinetic in [2+2] photocycloaddition. Solid-solutions with general formula [1H]BrxCl1-x (1 = 4-amino-cinnamic acid; 0 < x < 1) were...

Mineral analysis of river sand around Mt. Tsukuba for provenance estimation of Atamadai type pottery (2500–1500 BC) from Hinoki site (Tochigi, Japan)

A total of 77 pottery shards originating from the Middle Jomon period (2500–1500 BC) were excavated from the Hinoki site in Tochigi, Japan. Fifty-five of those were Atamadai type pottery, which might contain some temper fragments from the manufacturing process. The pottery shards were analyzed by X-ray diffractometry (XRD). The mineral analyses were compared with the river sands around Mt. Tsukuba to demonstrate the temper's origin of the Atamadai type pottery. Their XRD profiles revealed the following solid solutions which could be fingerprint minerals: biotite for the temper and plagioclase, and hornblende for the clay and temper. These minerals might indicate the origin of each sample because their d-spacings depended on the solid solution composition reflecting their geological characteristics.

Теплоемкость твердых растворов системы Er-=SUB=-2-=/SUB=-Ge-=SUB=-2-=/SUB=-O_7- Er-=SUB=-2-=/SUB=-Sn-=SUB=-2-=/SUB=-O-=SUB=-7-=/SUB=- в области 350-1000 K

Er_2Ge_2O_7–Er_2Sn_2O_7 solid solutions have been obtained using solid-state synthesis by burning the stoichiometric mixtures of the initial oxides in air in the temperature range of 1273–1473 K. The effects of temperature and solid solution composition on the specific heat have been examined by differential scanning calorimetry. The Er_2Ge_2O_7 thermodynamic functions have been calculated.

A Pseudo-Binary Diagram of the (Bi,Pb)-Sr-Ca-Cu-O System

A pseudo-binary phase diagram of the (Bi,Pb)-Sr-Ca-Cu-O system along the Bi1.6Pb0.4Sr2Can-1CunOx line is constructed. This resulting phase diagram shows three kinds of peritectic reactions, one eutectic reaction and one peritectoid reaction. The equilibrium solid phases in this diagram are the 2201 (n=1), 2212 (n=2), 2223 (n=3) and (Sr,Ca)CuO2 (n→∝) phases. The 2201 phase is solid solution which is stable at 1≤n≤1.2. The eutectic composition point is close to the maximum solid solution composition of the 2201 phase. The temperature interval between the peritectic reaction of L + (Sr,Ca)2CuO3 + (Sr,Ca)CuO2 → 2212 and the eutectic reaction of L → 2201 + 2212 is only about 3°C. For the composition of n=3, CaO and the liquid phase are stable at temperatures above 940°C. During the cooling, these two phases react peritectically to (Sr,Ca)2CuO3. At around 890°C, (Sr,Ca)2CuO3 reacts with the liquid to produce (Sr,Ca)CuO2. At around 865°C, (Sr,Ca)2CuO3 and (Sr,Ca)CuO2 react with the liquid to produce the 2212. The 2223 phase is transformed by a peritectoid reaction of the 2212 phase and residual (Sr,Ca)2CuO3, (Sr,Ca)CuO2.

Microwave Materials with High Q and Low Dielectric Constant for Wireless Communications.

ABSTRACTMicrowave dielectrics with high Q and low εr are expected for millimeterwave applications. In this paper the preparation and properties of some candidates for microwave dielectrics such as forsterite, willemite, alumina, corundum-type compounds, green phase of Y2BaCuO5 are presented. High purity forsterite has low εr of 7.0 high Q·f of 270000 GHz and τf of -65ppm/°C. Willemite also has low εr of 6.5, and high Q·f of 160000 GHz. Alumina has ultra high Q·f of 680000GHz with εr of 10.05, and τf of -60 ppm/°C. Mg4(Nb2-x Tax)O9 which belongs to corundum group has εr of 11.5, Q·f of 350000 GHz, and τf of -70ppm/°C. Y2Ba(Cu1/4Zn3/4)O5 which belongs to green phase group has εr of 15.4, Q·f of 220000 GHz. The τf’s of these materials, which are an important property for millimeterwave applications, have been adjusted to zero ppm/°C by the addition of rutile, or adjustment of solid solution composition.