The goal of energy landscape theory is to relate observable thermodynamic and dynamic properties to features of the underlying potential energy surface. Here we illustrate the approach with reference to the annealing of C60 and indicate how it may be used to design improved global optimisation algorithms.

Empirical Total Energy Tight Binding (TETB) has proven to be a fast and accurate method for calculating materials properties for various system, including bulk, surface and amorphous structures. The determination of the tight binding parameters from first-principles results is a multivariate, non-linear optimization problem with multiple local minima. Simulated annealing is an optimization method which is flexible and “guaranteed” to find a global minimum, opposed to classical methods like non-linear least squares algorithms. As an example results are presented for a nonorthogonal s,p parameterization for Silicon based on the NRL tight binding formalism.

Quantitative thermal stability test of glass materials against crystallization is accelerated through a vertical temperature-gradient furnace. In the furnace, zinc tellurite glass melt is sucked into a 75cm-long glass capillary tube (ID 1.5 × OD 8 mmø) and the tube is kept inside to be annealed under a temperature gradient of 300~800°C/50cm. The time to precipitate is determined to make a set of T-T-T (Time-Temperature-Transform) diagrams for different composition and thermal hysteresis. Crystallization is not observed for 65TeO2-35ZnO and 70TeO2-30ZnO (mol%) super-cooled glass melt after 4000s annealing but their stability decreased if the melts were once quenched to below their glass transition temperature before the annealing.

A systematical growth temperature and oxygen ambient dependency of SrTiO3/Si interface structures were investigated using a growth temperature gradient pulse laser deposition (PLD) system and cross sectional high resolution transmission electron microscopy (HRTEM). A SiO2 interfacial layer and an amorphized SrTiO3 layer were observed at the interface for the thin films grown on Si (100) at growth temperatures above 600°C. Our results show that at growth temperatures higher than 600°C, the formation of the amorphized SrTiO3 layer is strongly growth temperature and also oxygen partial pressure dependent.

Dispensing micron-scale dielectric materials can be achieved through the use of dielectrophoresis. Electrodes are designed to create a nonuniform electric field. This method is expected to be applicable for transfer of a wide range of dielectric powders as well as small, shaped components. Small, 150 μm diameter silica spheres, as well as sodium fluorescein powder have been dispensed by this method. Selecting the appropriate electrode geometry and electric field intensity controls the amount collected. As little as 1.0 μg of sodium fluorescein powder, and as much as 16 mg of silica beads have been collected, and repeatability within 10 % of the total amount dispensed has been achieved.

The field of combinatorial synthesis and “artificial intelligence” in materials science is still in its infancy. In order to develop and accelerated strategy in the discovery of new materials and processes, requires the need to integrate both the experimental aspects of combinatorial synthesis with the computational aspects of information based design of materials. In biology and organic chemistry, this has been accomplished by developing descriptors which help to specify “quantitative structure- activity relationships” at the molecular level. If materials science is to adopt these strategies as well, a similar framework of “QSARs” is required. In this paper, we outline some approaches that can lay the foundations for QSARs in materials science.

Thin films of carbon black-organic polymer composites have been deposited across two metallic leads, with sorption of vapors producing swelling-induced resistance changes of the detector films. To identify and classify vapors, arrays of such vapor sensing elements have been constructed in which each element of the array contains a different polymer as the insulating phase and a common conductor, carbon black, as the conducting phase. The differing gas-solid partition coefficients for the various polymers of the detector array produce a pattern of differential resistance changes that is used to classify vapors and vapor mixtures. The performance of this detector array system towards 2,4-dinitrotoluene, the predominant signature in the vapor phase above land mines, in the presence high concentrations of water or of acetone (as a selected volatile organic carbon vapor), has been evaluated.

We have developed a new methodology to design conducting polymers with pre-specified properties using genetic algorithms (GAs). The methodology combines GAs with the Negative Factor Counting (NFC) technique. NFC is a powerful technique to obtain the eigenvalues of large matrices without direct diagonalization.We present the results for a case study of polyanilines, one of the most important families of conducting polymers. The methodology proved to be able of generating automatic solutions for the problem of determining the optimum relative concentration for binary and ternary disordered polyaniline alloys exhibiting metallic properties. The methodology is completely general and can be used to design new classes of materials.

Diluted magnetic semiconductor (DMS) possesses charge and spin degrees of freedom leading to their interplay promising for novel devices. DMSs based on II-VI and III-V compound semiconductors have been extensively studied so far. Recently, the oxide semiconductors doped with transition metal magnetic impurity have attracted much attention for the possible high ferromagnetic Curie temperature. Here, we overview recent studies of the transparent oxide based DMSs, ZnO, TiO2, and SnO2 doped with 3d transition metals, by using the combinatorial materials synthesis and the high throughput screening.

We describe rhe application of simulated annealing and genetic algorithms to determine the ground-state of various classes of Lsing models. This problem is relevant to finding equilibrium contigurations(at zero Kelvin)of adsorbed monolayers, multi-component alloys, and magnetic systems. Because of the presence of metastable configurations (local minima) the detection of the ground-state (global minimum) is a non-trivial problem, especially in the case of complex interactions or frustrated systems. The speed of convergends analyzed for various model systems.

The combinatorial glass formation tester has been developed to determine the glass forming regions as quickly as possible. The 24 glass batches of about 1g were put into each carbon crucible on a carbon holder and heated in an electric furnace filled with dry nitrogen gas. After about a half an hour heating, the crucibles were taken out from the furnace and moved into the cooling chamber purged with dry nitrogen gas. The holder and the crucibles were moved on to a cooling stage to be cooled down quickly with a water flowing jacket together with nitrogen gas blowing. The time interval after taking out of the crucibles till the placement on the cooling stage was shortened as much as possible, resulting to be 10sec. The temperature of the melt in the crucibles was measured with an optical pyrometer to estimate the cooling rate. The top view of the crucibles on the holder was taken with a CCD camera during cooling. The CCD figures were stored on a computer for the judgments of the transparency of the samples in the crucibles to compile a glass forming region. The glass formation tester can manage 24 glass melting tests every 1 hours. In other words, the tester can produce at least 192 glass samples (24 x 8=192) within a day working time. The speed was roughly 100 times larger than the case of manual operation.

The Rational Discovery Framework(TM) is a novel approach for providing computational guidance in the high-throughput discovery process. The Framework uses a proprietary machine-learning algorithm to construct predictive models from existing experimental data. These predictive models are used to computationally screen the contents of large virtual libraries. A variety of experimental design techniques can be brought to bear on the results of a virtual library screen in order to suggest an optimal set of synthesis candidates for the next round of experimentation. We have demonstrated the power and generality of the Rational Discovery Framework in a series of proofs of concept. Here we present an overview of the Framework as well as the results of studies aimed at developing predictive models for materials properties: ferromagnetism in ordered and disordered transition-metal alloys; and prediction of Tc values for superconductors.

A combinatorial material synthesis with temperature gradient heating system was employed to optimizing growth parameters for oxide growth on Si substrate. From the obtained results, it was found the dielectric property depends on the growth temperature as well as the composition. The interface structures were investigated by high resolution electron microscopy with a series of specimens fabricated by micro sampling method. The results showed that amorphous oxide region and SiO2 layer were formed at the interface. It was speculated that the amorphous oxide region contributed to the reduction of the dielectric property. To avoid the amorphous and SiO2 formation at the oxide/Si interface, a few kinds of intermediate layers were inserted and tested to find the possibility of abrupt interface formation.

We have used our combinatorial pulsed laser deposition system to in-situ fabricate epitaxial Ba1-xSrxTiO3 thin film composition spreads on (100) LaAlO3 substrates. Multimode quantitative microwave microscopy was used to perform dielectric characterization of the spreads at multiple microwave frequencies simultaneously. Systematic variation in dielectric properties as a function of composition is studied. The multi-mode measurements allow frequency dispersion studies. We observe strong composition-dependent dielectric dispersion in Ba1-xSrxTiO3.

Studies on scanning electron-beam dielectric microscopy (SEDM) are reported. This microscopy technique is used for determining the temperature coefficient distribution of dielectric materials using an electron-beam as a heat source instead of a light beam as in photothermal dielectric microscopy. This microscopy technique, which has the ability to simultaneously observe SEM images and the material composition by EPMA, has a resolution better than that of photothermal dielectric microscopy. To demonstrate the usefulness of this technique, the two-dimensional image of a two-phase composite ceramic composed of TiO2 and Bi2Ti4O11 is measured. To shorten a measurement time, a new type of SEDM for measuring the real time transient response caused by a single pulsed electron-beam is also successfully developed. Finally, a quantitative measurement method of temperature coefficient is also developed.

We illustrate how emerging methods in artificial intelligence (AI) may be useful in materials science. Historically, these methods were developed in the area of materials process control and, more recently, in the nascent field of materials discovery. However, machine intelligence is of much broader import and our primary objective here is to illustrate how such methods may be used to circumvent some serious roadblocks in the computer simulation of a significant class of computationally hard problems in materials science. This is illustrated by a new approach to solving the dynamics of the N-body problem for large numbers of objects of essentially arbitrarily complex geometry or interaction potential. The approach, based on a particulate artificial neural net dynamics algorithm (PANNDA) is more than two orders of magnitude faster than existing methods when applied to large systems and is only marginally slower (∼10%) than the theoretical lower limiting case of hard spheres. In this method an artificial neural net is trained to predict accurately the time to next collision for binary encounters spanning the Hilbert space of relative positions, orientations and momenta (linear and angular). This approach, which can be extended to soft complex systems, enables construction of exact, albeit numerical, models for the thermodynamic, transport and non-equilibrium properties of very large ensembles of hard or soft objects of arbitrarily complex shape or interaction potential. Our results open up the possibility of immediate application to an usually wide spectrum of contemporary computationally intractable “hard” problems ranging from granular materials with asperities through inclusion of complex many-body terms in the intermolecular interaction in molecular dynamics calculations of complex fluids and polymers.

A scanning microwave microscope (Sm M) for high-throughput characterization of combinatorial dielectric materials has been developed using a lumped constant resonator probe. The probe consists of a microwave oscillator module equipped with a thin conducting needle and an outer conductor ring, which detects the dielectric constant of the sample just beneath the needle as a frequency shift of the resonator. The quantitative analysis of the dielectric constant for the bulk and the thin-film samples was carried out based on the measurement of gap-length dependence of the frequency shift. The analysis method was successfully applied to the characterization of composition-spread BaxSr1-xTiO3 thin film sample. The evaluation of far-field contribution to the frequency shift was found to be crucial for the accurate determination of dielectric constant especially in the characterization of combinatorial thin films.

We show here three different ways of combinatorial experiments for achieving precise control of dopant concentration in ZnO thin films. Alternating ablation of highly pure single crystal target and ceramics target doped with concentrated Ga dopant yielded in a systematic control of Ga concentration with keeping minimal contamination of undesired impurity. Secondary ion mass spectroscopy for a stack of several ZnO films grown at different temperatures under a constant exposure of N radical gave us a systematic calibration curve for the N concentration. With using a special heating method to give a controlled temperature gradient on a substrate, we demonstrate that continuous spread of N concentration can be built in a film on a substrate with keeping constant Ga concentration. Such systematic experiments taking into account the “combinatorial” concept enable us to make ZnO films with controlled dopant concentrations.

A new combinatorial pulsed laser deposition system has been developed for rapid optimization of epitaxial growth process by using a carrousel type masking plate. Under in-situ monitoring of growing surface with reflection high energy electron diffraction, eight films with different compositions or preparation parameters can be fabricated on a single substrate. By using this system, we have succeeded in the one lot optimization of YBa2Cu3O7-d(YBCO), PrGaO3, SrO and BaO film growths on the B-site (TiO2) terminated SrTiO3(001) substrates. Key results from these experiments include the high sensitivity of YBCO film crystallinity to the laser focusing as well as of growth behavior of epitaxial SrO and BaO films to the crystal habit with the underlying atomic layers.