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Mr. BOLAND. May I ask one more question, Mr. Chairman?

Mr. THOMAS. Yes.

Mr. BOLAND. One of the problems that concerns me in this area of space exploration is that oceanography is suffering because of our effort in space. Would you say this is true?

Dr. VAN ALLEN. I do not really see how.

Mr. BOLAND. We are spending a lot more money in this area than we are in oceanography and perhaps the values that we might get out of our knowledge of the ocean, the depths of the ocean, oceanic life and composition of the ocean, might be more significant to mankind than those we may get out of space exploration.

Mr. YATES. The President has suggested that the field of space is

a new ocean.

Mr. BOLAND. Is there any concern, would you say, about this?

Dr. VAN ALLEN. Many people say the great expenditures on space are preventing advances in medicine, and the prevention of diseases, but I do not see how one can defend that view in any detailed way. Who is actually held up for lack of money in medicine? Likewise, I do not think that there are competent oceanographers who are being held up for lack of support, either.

Mr. BOLAND. That is fine. I am glad to get your views.

Mr. THOMAS. Certainly, you have been most kind and gracious, Dr. Van Allen. You have made a wonderful statement and again let me repeat our many thanks. We are certainly looking forward to hearing our other distinguished guests.

SOLID STATE SCIENCE

STATEMENT OF DR. FREDERICK SEITZ

Dr. WATERMAN. The next of our distinguished guests today, Mr. Chairman, is Dr. Frederick Seitz, from the University of Illinois. Mr. THOMAS. Doctor, it is a privilege and pleasure to have you with us. We shall be glad to hear you talk. Take as much time as you think you can reasonably give us.

Dr. SEITZ. Thank you, Mr. Chairman. It is an honor to be here. It is also a pleasure to be with Dr. Waterman and his group. Dr. Waterman deserves very special commendation from all scientists for the outstanding service he has rendered in making science available to the service of the Nation.

In as short a time as is practical, I would like to give you a picture of the field of solid state science. By the present time, this field has grown into one of the major areas of research and development. Although it may not have all of the popular appeal of space science at present, it is the source of many important investigations and devices which do support those areas which receive so much attention. The field has not only broadened our knowledge of the world in which we live but has given us a number of devices without which we could not carry on our highly complex modern society.

TYPES OF SOLIDS

All of us are familiar with the normal three states of matter. We learn about them in our first association with science, that is, we learn about gases, liquids, and solids. The solids are distinguished by the fact that they tend to resist deformation when we attempt to form them. Actually, they never completely resist deformation. Any solid can either be bent or broken if it is in our interest to cause such a change.

In actual fact there are three broad types of solids. The first I will discuss has a very interesting history. It is the supercooled liquid normally known as a glass. In this room we encounter it in the form of the window panes, the chandeliers, and the glass ashtrays on the tables. Only a few chemical compounds in the inorganic world are glass formers. You meet them rather rarely in the glassy form in nature, although they are frequently encountered near volcanos in the form of obsidian which the Indians often used for arrow heads. As I commented above, the glasses are liquids which have cooled so quickly that they have not had a chance to freeze.

A number of organic materials can also be supercooled into glasses. For example, almost all varieties of transparent candy, other than old fashioned rock candy, are glasseous forms of sugar.

Looking at affairs from the atomic scale, a glass is characterized by the fact that the atomic arrangement becomes random once you get very far from a given atom. This is the situation one is familiar with if he examines apples or oranges piled in a bushel basket. The apples immediately around a given one take positions which are influenced by the given apple. However, if you move very far away from it you find no regular arrangement. There is no long-range order.

Another very important class of solid is the polymer. In this room you meet it in various forms. There are the natural polymers such as wood and leather, and the synthetic polymers such as the frames in your spectacles or the normal plastic containers in which so many things are packaged these days. Polymers are composed of very long molecules or chains which are bound together into bundles by chemical forces. Nature tends to use the polymer a great deal. The rubber in your tires is composed of polymers. Your muscles provide another example. In fact, a large part of the connective tissue in the human body is polymeric in form.

The man-made polymers, or synthetic polymers, are undergoing a very great development at the present time. They represent one of the miracles of modern chemistry. You will recall that when Khruschev visited the United States in 1959 one of his goals was a trip to the Du Pont Co. There is no doubt that he wanted to open the door to information regarding the development of polymers since they have provided us with so many useful materials for both peaceful and military affairs.

The third type of solid, and the one which has given us the greatest amount of information even though we also learn a great deal from glasses and polymers, is represented by the crystalline materials. They have a very high degree of internal order and have been the subject of a great deal of fine scientific work. I shall concentrate on them in the following presentation.

If you travel in the great western mountains and look into a typical streambed, you will often see glistening rectangular stones. These are the feldspars. They usually are individual crystals of the component rocks or minerals. Naturally many of the specimens are weathered as a result of erosion. Nevertheless their regular crystalline form is quite evident. Most of the inorganic materials which you meet in nature are crystalline, although you may have to look under a microscope to see the individual crystals, or grains as they are sometimes called.

If you glance around this room, you will note the marble in the fireplace. It is composed of crystals or grains. The individual crystals are arranged somewhat randomly relative to one another but there is a high degree of atomic order in every crystal. The model of rock salt I have on this table provides an excellent example of the type of atomic arrangement which occurs in a typical crystal of a very simple kind.

Looking somewhat farther, you will see the metal in the doorknobs. or in the electric outlets. Such metals usually are crystalline; in fact, the atomic arrangement occurring in brass is the so-called cubic closepacked one. It is found in many other metals such as the bronzes, aluminum, copper, gold and so forth.

Normally it is necessary to look under a microscope to see the individual crystalline grains. However, the grains often are visible in a simple casting with the unaided eye. For example, if you look into a cast doorknob which has been outside a good deal and has been handled frequently so that there is a certain amount of corrosion, you will often see grains or crystals of the order of an eighth of an inch in size. I might refresh your memories by mentioning that the atoms in all forms of matter are composed of a very small compact center called the nucleus which is surrounded by an electron cloud. The charge on the nucleus and the number of electrons vary from one species of atom to another. The nuclear charge and the number of compensating electrons determine the chemical species to which the atom belongs.

The electron clouds on neighboring atoms in solids are in contact with one another, that is, they form a chemical bond. Most of the detailed properties of solids can be related to the behavior of the electron clouds surrounding the nuclei.

The crystalline solids can be divided into a number of types, all of which are familiar to you in some form. First, there are the metals which I mentioned earlier. They have a typical shiny luster; they are cold to the touch; they are good electrical conductors; and often are very malleable, at least when properly made. Their great malleability and strength are what made them important to man when they were first produced. It turns out that about 70 percent of all the pure elements found in nature are metallic in solid form. Moreover, they tend to combine well with one another to form alloys, such as brass and bronze or steel.

The metals usually contain free electrons which can conduct an electric current with ease. The orbital electrons which determine the chemical binding are able to wander freely through the lattice so that they can be influenced by an electric field and hence produce an electric current. The ease with which the electrons can be made to move

increases in the metals at low temperatures so that they become better and better conductors. A few metals have the characteristic that they become superconductors at low temperatures; that is, their electrical resistivity vanishes completely. Such materials are of very great interest at the present time, both because we are beginning to get an understanding of the origin of superconductivity and because they offer promise of giving us some highly interesting and practical devices.

The insulating solids form another major class of solid crystalline material. There are three broad classes. The first are the salts, rock salt or ordinary table salt being an example. They tend to be slightly soluble in water and are distinguished by the fact that the solution will conduct an electric current as a result of the migration of the atoms or ions rather than by the simple migration of free electrons, as occurs in metals. Many salts are good electrolytic conductors even in solid form at sufficiently high temperatures.

A second type of insulating material is the valence crystal. Diamonds and numerous other gems belong in this category. They are very hard and strong. The factors which are used to distinguish them need not be discussed in detail here. The main point I should make is that neighboring atoms are tightly bound to one another by forces which are highly directional. As a result they have very great strength without much ductility. I should add that silicon carbide, a well-known and common abrasive, is an excellent and useful example. Third, I should mention the organic crystals. A large number of organic materials will crystallize quite readily. A typical example familiar to all of you is naphthalene, the component of ordinary moth balls. Many organic crystals are highly colored and are known to you as the pigments in a wide variety of paints, particularly the colored automobile finishes.

Another general class of solid which has received a great deal of attention in the last quarter century is the semiconductor which appears in many electronic devices. It is basically an insulator but becomes an electronic conductor at sufficiently high temperature. I mentioned earlier that the metals have electrons which are completely free at all temperatures and which become more and more mobile at low temperatures. The electrons in the semiconductors are free at sufficiently high temperatures but become trapped or bound at low temperatures. Thus, they tend to be insulators near the absolute zero of temperature but may be quite good conductors at higher temperatures. Some solids such as silicon and germanium are semiconductors even when very pure, that is, the ordinary valence electrons are freed at high temperatures. These are called intrinsic semiconductors. On the other hand, there are other solids which become semiconductors only when they contain impurities, the electrons associated with the impurities becoming free at high temperatures. This is true, for example, in zinc oxide and in certain conducting diamonds. They are called impurity semiconductors.

Silicon and germanium, which now form the basis of such a large part of the electronic industry, being used in diodes and in transistors, were chemical curiosities before World War II. It required the extensive investigations associated with wartime work to bring their full potentialities to light.

RESEARCH ON CRYSTALLINE SOLIDS

Let me discuss next some of the major areas of research dealing with crystalline solids, starting first with fundamental topics and then working up to matters of current interest.

Soon after the natural single crystals, such as the feldspars which I mentioned earlier, received attention, investigators started examining the properties of the individual grains by cutting them out of massive specimens and studying them. One can, for example, examine the optical, electrical, thermal, and mechanical properties of such specimens. This led to the accumulation of a very wide variety of facts often having practical consequences. It was discovered, for example, that some crystals develop an electrical charge when compressed. Such specimens form the basis for good microphones or record player pickups.

One of the great advances made in the present century in the study of crystals centers about the development of techniques for growing individual crystals of many compounds which are not found readily in nature. Such specimens have found myriads of uses. I might mention, for example, that the jewels in a good watch are made of such synthetic crystals, just as are the crystalline units in the transistor radio which you can carry about in your travel bag.

It is rather interesting to note in passing that radioactivity was discovered at the end of the last century by the physicist Becquerel, who was primarily interested in the properties of natural crystals. He happened incidentally to observe that some of the crystals in his laboratory gave off penetrating radiations.

INTRODUCTION OF ASTRONAUTS TO THE COMMITTEE

Mr. THOMAS. Gentlemen, if you will permit a brief interruption at this time which I am sure we shall all enjoy, the Administrator of the National Aeronautics and Space Administration, Mr. Webb, has just come in and has with him the three astronauts whom we shall be glad to meet at this time.

Mr. WEBB. I think it is clear to all of you who have appeared in this room over the years that this committee is extremely interested in having the work of the Government agencies well done, efficiently done, no unnecessary money expended, but I should say in the field of science and technology this committee has given wonderful support to the things which were really important to the country.

In Bob Gilruth, the manager of Project Mercury, I would like to submit a man who spends your money effectively and efficiently and gets many byproducts.

In Alan Shepard, the man who flew the first mission in the MERCURY capsule, and proved what had hitherto been unknown, although largely felt to be an acceptable risk, that the man-machine system of MERCURY would really work on reentry as well as on blastoff.

In Gus Grissom, we have the man who proved that the first flight was not a one-time wonder but really was an inherent capability of the system.

Of course, in John Glenn we have the man who had the honor and the responsibility of representing all seven astronauts in com

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