How to Use the Spectrum Energy Charts

The Difference Between a Catalog and a Map

A materials catalog tells you what someone already discovered about a material, filed under the heading they discovered it in. Silicon is a semiconductor. Lead is shielding. Sodium iodide is a scintillator. These are labels — useful, but limited to what's already known.

The Spectrum Energy charts ask a different question: What does this material do with each type of energy? Does it absorb it? Convert it? Reflect it? Block it? Pass it through unchanged? The answer is mapped across every energy band — infrared, visible, ultraviolet, X-ray, gamma, particle kinetic energy, thermal energy, and neutrons.

The result is a coupling map. And a coupling map can find materials that no catalog will — because it searches by what the atoms do, not by what category someone filed them under.

This matters when the job requires a combination of properties that spans multiple fields. If you need a material that is simultaneously a semiconductor, a liquid at moderate temperature, self-healing under radiation, and transparent to neutrons, no single catalog contains that combination. The semiconductor catalog doesn't sort by neutron absorption. The nuclear materials catalog doesn't sort by bandgap. The material you need may already exist, sitting in a gap between fields that don't talk to each other.

The Method in Practice

Rather than describe the method abstractly, here is a real engineering problem that demonstrates it.

The Spectrum Energy Reactor — a nuclear reactor that converts fission energy through multiple pathways simultaneously — needs a material for its primary converter that:

1. Produces free electrons when struck by a high-energy particle
2. Is liquid at 130–300°C
3. Does not absorb neutrons significantly
4. Has high enough carrier mobility that freed electrons reach an electrode before recombining

The Conventional Search

Ask a nuclear engineer for a liquid semiconductor that works under radiation. They will point to the published literature on selenium-sulfur alloys and perhaps mention solid-state detectors like cadmium telluride. The list is short because the question spans two fields that rarely overlap.

The Chart-Based Search

Start with the mechanism, not the category. The current solution — a selenium-sulfur alloy — works because of specific atomic properties. Selenium and sulfur are both Group 16 elements: six outer electrons, moderate bandgap, and a chain-forming molecular structure that persists in the liquid state. When a particle rips through, it breaks bonds along its path, freeing electrons. The liquid reforms the bonds — self-healing. Published research has confirmed this behavior under alpha particle bombardment (Nullmeyer et al., 2018, Nature Scientific Reports).

Identify what controls each requirement. Each behavior traces back to an atomic property:

These properties are independent. A material can be an excellent semiconductor and a terrible neutron absorber at the same time. The charts show both on the same map.

Search by those properties. Every Group 16 element has six outer electrons and forms chains:

Every binary and ternary combination is a candidate liquid semiconductor:

• Se-S — the current baseline, melts at 130–140°C
• Se-Te — higher operating temperature, lower neutron absorption, tunable bandgap
• S-Te — widest melting range, untested as liquid semiconductor
• Se-S-Te — three-component alloy with three independent tuning variables

None of the alternatives have been tested for this application. The conventional search would never find them because they are not filed under "radiation detector" or "nuclear material." The property search finds them immediately.

Expand beyond the obvious. Group 15 elements (arsenic, antimony) form similar network structures. Arsenic-selenium and antimony-selenium glasses are known to maintain semiconducting properties in the liquid state. Their behavior under particle bombardment has never been studied. A property search flags them as candidates.

Catch false positives. Cadmium telluride is the best room-temperature solid-state particle detector available. A conventional search would place it at the top of the list. But the charts show cadmium's neutron absorption cross-section: 2,520 barns. Inside a reactor core, it would shut down the chain reaction. The electronic properties are perfect. The nuclear properties are disqualifying. The charts show both — the catalog shows only one.

Engineering New Materials

Once the method reveals which atomic property controls which behavior, it opens the door to designing materials that don't exist yet.

For the liquid semiconductor application, five design levers are largely independent:

An engineered alloy could optimize all five. For example: a selenium-tellurium base (tuning bandgap and melting point) with trace arsenic doping (tuning carrier mobility) — a material designed from atomic principles for a job that didn't exist before.

The Method Applies to Every Material

The liquid semiconductor is one example. The same approach works for any material selection problem:

• Finding a gamma-to-light converter — what atomic properties produce this? High atomic number (stops gamma), wide bandgap (emits visible photons), specific crystal symmetry (allows radiative relaxation). Search for materials with all three — not just materials already labeled "scintillator."

• Matching a photovoltaic cell to a specific light source — if the source emits at 415 nanometers, search for semiconductors with bandgaps matching that wavelength, regardless of what application they were developed for.

• Finding a thermoelectric material that survives inside a reactor — search for materials combining high Seebeck coefficient, low thermal conductivity, and radiation tolerance. The charts flag half-Heusler alloys like TiNiSn — mechanically robust, radiation hard, and effective at reactor operating temperatures.

In every case: define the job by what it does, identify the atomic properties that control it, search the charts by those properties. The charts return candidates that a category search would miss.

© 2026 David R. Young — Spectrum Energy Research Foundation CC BY-NC-SA 4.0 for research, education, and non-commercial use. Commercial use requires a separate license from the Foundation.