Cover: Principles of Inorganic Materials Design, Third Edition by John N. Lalena, David A. Cleary and Olivier B.M. Hardouin Duparc

Principles of Inorganic Materials Design

Third Edition

John N. Lalena

Physical Scientist

David A. Cleary

Gonzaga University

Olivier B.M. Hardouin Duparc

École polytechnique Institut Polytechnique Paris

No alt text required.

Foreword to Second Edition

Materials science is one of the broadest of the applied science and engineering fields since it uses concepts from so many different subject areas. Chemistry is one of the key fields of study, and in many materials science programs, students must take general chemistry as a prerequisite for all but the most basic of survey courses. However, that is typically the last true chemistry course that they take. The remainder of their chemistry training is accomplished in their materials classes. This has served the field well for many years, but over the past couple of decades, new materials development has become more heavily dependent upon synthetic chemistry. This second edition of Principles of Inorganic Materials Design serves as a fine text to introduce the materials student to the fundamentals of designing materials through synthetic chemistry and the chemist to some of the issues involved in materials design.

When I obtained my BS in ceramic engineering in 1981, the primary fields of materials science – ceramics, metals, polymers, and semiconductors – were generally taught in separate departments, although there was frequently some overlap. This was particularly true at the undergraduate level, although graduate programs frequently had more subject overlap. During the 1980s, many of these departments merged to form materials science and engineering departments that began to take a more integrated approach to the field, although chemical and electrical engineering programs tended to cover polymers and semiconductors in more depth. This trend continued in the 1990s and included the writing of texts such as The Production of Inorganic Materials by Evans and De Jonghe (Prentice Hall College Division, 1991), which focused on traditional production methods. Synthetic chemical approaches became more important as the decade progressed and academia began to address this in the classroom, particularly at the graduate level. The first edition of Principles of Inorganic Materials Design strove to make this material available to the upper division undergraduate student.

The second edition of Principles of Inorganic Materials Design corrects several gaps in the first edition to convert it from a very good compilation of the field into a text that is very usable in the undergraduate classroom. Perhaps the biggest of these is the addition of practice problems at the end of every chapter since the second best way to learn a subject is to apply it to problems (the best is to teach it), and this removes the burden of creating the problems from the instructor. Chapter 1, Crystallographic Considerations, is new and both reviews the basic information in most introductory materials courses and clearly presents the more advanced concepts such as the mathematical description of crystal symmetry that are typically covered in courses on crystallography of physical chemistry. Chapter 10, Mechanical Properties, has also been expanded significantly to provide both the basic concepts needed by those approaching the topic for the first time and the solid mathematical treatment needed to relate the mechanical properties to atomic bonding, crystallography, and other material properties treated in previous chapters. This is particularly important as devices use smaller active volumes of material, since this seldom results in the materials being in a stress‐free state.

In summary, the second edition of Principles of Inorganic Materials Design is a very good text for several applications: a first materials course for chemistry and physics students, a consolidated materials chemistry course for materials science students, and a second materials course for other engineering and applied science students. It also serves as the background material to pursue the chemical routes to make these new materials described in texts such as Inorganic Materials Synthesis and Fabrication by Lalena and Cleary (Wiley, 2008). Such courses are critical to insure that students from different disciplines can communicate as they move into industry and face the need to design new materials or reduce costs through synthetic chemical routes.

Martin W. Weiser

Martin earned his BS in ceramic engineering from Ohio State University and MS and PhD in Materials Science and Mineral Engineering from the University of California, Berkeley. At Berkeley he conducted fundamental research on sintering of powder compacts and ceramic matrix composites. After graduation he joined the University of New Mexico (UNM) where he was a visiting assistant professor in chemical engineering and then assistant professor in mechanical engineering. At UNM he taught introductory and advanced materials science classes to students from all branches of engineering. He continued his research in ceramic fabrication as part of the Center for Micro‐Engineered Ceramics and also branched out into solder metallurgy and biomechanics in collaboration with colleagues from Sandia National Laboratories and the UNM School of Medicine, respectively.

Martin joined Johnson Matthey Electronics in a technical service role supporting the Discrete Power Products Group (DPPG). In this role he also initiated JME’s efforts to develop Pb‐free solders for power die attach that came to fruition in collaboration with John N. Lalena several years later after JME was acquired by Honeywell. Martin spent several years as the product manager for the DPPG and then joined the Six Sigma Plus organization after earning his Six Sigma Black Belt working on polymer/metal composite thermal interface materials (TIMs). He spent the last several years in the R&D group as both a group manager and principle scientist where he lead the development of improved Pb‐free solders and new TIMs.

Foreword to First Edition

Whereas solid‐state physics is concerned with the mathematical description of the varied physical phenomena that solids exhibit and the solid‐state chemist is interested in probing the relationships between structural chemistry and physical phenomena, the materials scientist has the task of using these descriptions and relationships to design materials that will perform specified engineering functions. However, the physicist and the chemist are often called upon to act as material designers, and the practice of materials design commonly requires the exploration of novel chemistry that may lead to the discovery of physical phenomena of fundamental importance for the body of solid‐state physics. I cite three illustrations where an engineering need has led to new physics and chemistry in the course of materials design.

In 1952, I joined a group at the MIT Lincoln Laboratory that had been charged with the task of developing a square B–H hysteresis loop in a ceramic ferrospinel that could have its magnetization reversed in less than 1 μs by an applied magnetic field strength less than twice the coercive field strength. At that time, the phenomenon of a square B–H loop had been obtained in a few iron alloys by rolling them into tapes so as to align the grains, and hence the easy magnetization directions, along the axis of the tape. The observation of a square B–H loop led Jay Forrester, an electrical engineer, to invent the coincident‐current, random‐access magnetic memory for the digital computer since, at that time, the only memory available was a 16 × 16 byte electrostatic storage tube. Unfortunately, the alloy tapes gave too slow a switching speed. As an electrical engineer, Jay Forrester assumed the problem was eddy‐current losses in the tapes, so he had turned to the ferrimagnetic ferrospinels that were known to be magnetic insulators. However, the polycrystalline ferrospinels are ceramics that cannot be rolled! Nevertheless, the Air Force had financed the MIT Lincoln Laboratory to develop an air defense system of which the digital computer was to be a key component. Therefore, Jay Forrester was able to put together an interdisciplinary team of electrical engineers, ceramists, and physicists to realize his random‐access magnetic memory with ceramic ferrospinels.

The magnetic memory was achieved by a combination of systematic empiricism, careful materials characterization, theoretical analysis, and the emergence of an unanticipated phenomenon that proved to be a stroke of good fortune. A systematic mapping of the structural, magnetic, and switching properties of the Mg–Mn–Fe ferrospinels as a function of their heat treatments revealed that the spinels, in one part of the phase diagram, were tetragonal rather than cubic and that compositions, just on the cubic side of the cubic–tetragonal phase boundary, yield sufficiently square B–H loops if given a carefully controlled heat treatment. This observation led me to propose that the tetragonal distortion was due to a cooperative orbital ordering on the Mn3+ ions that would lift the cubic‐field orbital degeneracy; cooperativity of the site distortions minimizes the cost in elastic energy and leads to a distortion of the entire structure. This phenomenon is now known as a cooperative Jahn–Teller distortion since Jahn and Teller had earlier pointed out that a molecule or molecular complex, having an orbital degeneracy, would lower its energy by deforming its configuration to a lower symmetry that removed the degeneracy. Armed with this concept, I was able almost immediately to apply it to interpret the structure and the anisotropic magnetic interactions that had been found in the manganese–oxide perovskites since the orbital order revealed the basis for specifying the rules for the sign of a magnetic interaction in terms of the occupancies of the overlapping orbitals responsible for the interatomic interactions. These rules are now known as the Goodenough–Kanamori rules for the sign of a superexchange interaction. Thus an engineering problem prompted the discovery and description of two fundamental phenomena in solids that ever since have been used by chemists and physicists to interpret structural and magnetic phenomena in transition metal compounds and to design new magnetic materials. Moreover, the discovery of cooperative orbital ordering fed back to an understanding of our empirical solution to the engineering problem. By annealing at the optimum temperature for a specified time, the Mn3+ ions of a cubic spinel would migrate to form Mn‐rich regions where their energy is lowered through cooperative, dynamic orbital ordering. The resulting chemical inhomogeneities acted as nucleating centers for domains of reverse magnetization that, once nucleated, grew away from the nucleating center. We also showed that eddy currents were not responsible for the slow switching of the tapes, but a small coercive field strength and an intrinsic damping factor for spin rotation.

In the early 1970s, an oil shortage focused worldwide attention on the need to develop alternative energy sources, and it soon became apparent that these sources would benefit from energy storage. Moreover, replacing the internal combustion engine with electric‐powered vehicles, or at least the introduction of hybrid vehicles, would improve the air quality, particularly in big cities. Therefore, a proposal by the Ford Motor Company to develop a sodium–sulfur battery operating at 3008°C with molten electrodes and a ceramic Na+‐ion electrolyte stimulated interest in the design of fast alkali ion conductors. More significant was interest in a battery in which Li+ rather than H+ is the working ion, since the energy density that can be achieved with an aqueous electrolyte is lower than what, in principle, can be obtained with a nonaqueous Li+‐ion electrolyte. However, realization of a Li+‐ion rechargeable battery would require identification of a cathode material into/from which Li+ ions can be inserted/extracted reversibly. Brian Steele of Imperial College, London, first suggested the use of TiS2, which contains TiS2 layers held together only by van der Waals S2––S2– bonding; lithium can be inserted reversibly between the TiS2 layers. M. Stanley Whittingham's demonstration was the first to reduce this suggestion to practice while he was at the Exxon Corporation. Whittingham's demonstration of a rechargeable Li–TiS2 battery was commercially nonviable because the lithium anode proved unsafe. Nevertheless, his demonstration focused attention on the work of the chemists Jean Rouxel of Nantes and R. Schöllhorn of Berlin on insertion compounds that provide a convenient means of continuously changing the mixed valency of a fixed transition metal array across a redox couple. Although work at Exxon was halted, their demonstration had shown that if an insertion compound, such as graphite, was used as the anode, a viable lithium battery could be achieved, but the use of a less electropositive anode would require an alternative insertion‐compound cathode material that provided a higher voltage versus a lithium anode than TiS2. I was able to deduce that no sulfide would give a significantly higher voltage than that obtained with TiS2 and therefore that it would be necessary to go to a transition metal oxide. Although oxides other than V2O5 and MoO3, which contain vandyl or molybdyl ions, do not form layered structures analogous to TiS2, I knew that LiMO2 compounds exist that have a layered structure similar to that of LiTiS2. It was only necessary to choose the correct M3+ cation and to determine how much Li could be extracted before the structure collapsed. That was how the Li1−x CoO2 cathode material was developed, which now powers the cell telephones and laptop computers. The choice of M = Co, Ni, or Ni0.5+δ Mn0.5−δ was dictated by the position of the redox energies and an octahedral site preference energy strong enough to inhibit migration of the M atom to the Li layers on the removal of Li. Electrochemical studies of these cathode materials, and particularly of Li1−x Ni0.5+δ Mn0.5−δ O2, have provided a demonstration of the pinning of a redox couple at the top of the valence band. This is a concept of singular importance for interpretation of metallic oxides having only M–O–M interactions, of the reason for oxygen evolution at critical Co(IV)/Co(III) or Ni(IV)/Ni(III) ratios in Li1−x MO2 studies, and of why Cu(III) in an oxide has a low‐spin configuration. Moreover, exploration of other oxide structures that can act as hosts for insertion of Li as a guest species has provided a means of quantitatively determining the influence of a counter cation on the energy of a transition metal redox couple. This determination allows tuning of the energy of a redox couple, which may prove important for the design of heterogenous catalysts.

As a third example, I turn to the discovery of high‐temperature superconductivity in the copper oxides, first announced by Bednorz and Müller of IBM Zürich in the summer of 1986. Karl A. Müller, the physicist of the pair, had been thinking that a dynamic Jahn–Teller ordering might provide an enhanced electron–phonon coupling that would raise the superconductive critical temperature TC3+2+2+T copper oxides; however, the enhanced electron–phonon coupling is not due to a conventional dynamic Jahn–Teller orbital ordering, but rather to the first‐order character of the transition from localized to itinerant electronic behavior of ‐bonding Cu: 3d electrons of (2y) symmetry in CuO planes. In this case, the search for an improved engineering material has led to a demonstration that the celebrated Mott–Hubbard transition is generally not as smooth as originally assumed, and it has introduced an unanticipated new physics associated with bond length fluctuations and vibronic electronic properties. It has challenged the theorist to develop new theories of the crossover regime that can describe the mechanism of superconductive pair formation in the copper oxides, quantum critical‐point behavior at low temperatures, and an anomalous temperature dependence of the resistivity at higher temperatures as a result of strong electron–phonon interactions.

These examples show how the challenge of materials design from the engineer may lead to new physics as well as to new chemistry. Sorting out of the physical and chemical origins of the new phenomena fed back to the range of concepts available to the designer of new engineering materials. In recognition of the critical role in materials design of interdisciplinary cooperation between physicists, chemists, ceramists, metallurgists, and engineers that is practiced in industry and government research laboratories, John N. Lalena and David A. Cleary have initiated, with their book, what should prove to be a growing trend toward greater interdisciplinarity in the education of those who will be engaged in the design and characterization of tomorrow's engineering materials.

John B. Goodenough