All articles A–Z

Solid-phase synthesis

Solid-phase synthesis is a chemical method in which the growing molecule is attached to an insoluble solid support, introduced by Bruce Merrifield in 1963 and now used to make peptides, oligonucleotides, and drug-discovery libraries.

Solid-propellant rocket

A solid-propellant rocket, also called a solid rocket motor, is a rocket with fuel and oxidizer cast together as a solid grain that burns from exposed surfaces.

Solid-state battery

A solid-state battery, also called a solid battery, is a rechargeable battery in which a solid electrolyte replaces the flammable liquid of lithium-ion cells, enabling lithium-metal anodes.

Solid-state circuit breaker

A solid-state circuit breaker is an electrical protection device that interrupts fault current with power semiconductor switches in microseconds, aimed mainly at fast-rising DC fault currents.

Oct 22, 2026

Solid-state composite cathode

A solid-state composite cathode is the positive electrode of an all-solid-state battery, a solid mix of active material, solid electrolyte, carbon, and binder that must conduct ions and electrons.

Solid-state drive

A solid-state drive (SSD) is a data storage device that uses non-volatile NAND flash memory instead of spinning platters, making it faster and more shock-resistant than a hard disk drive.

Solid-state electronics

Solid-state electronics is the branch of electronics in which current flows through solid semiconductors, chiefly silicon, rather than vacuum tubes; born with the 1947 Bell Labs transistor, it underlies virtually every modern electronic product.

Solid-state fermentation

Solid-state fermentation (SSF): microbial cultivation on moist solid substrates with little or no free water, used for koji, daqu, enzymes, organic acids, and biofuels; distinguished from submerged fermentation by low moisture, fungal growth, and heat-transfer scale-up limits.

Oct 22, 2026

Solid-state high-harmonic generation

Solid-state high-harmonic generation, or solid-state HHG, is the emission of high-order harmonics of an intense laser from a crystalline solid, first observed in bulk ZnO in 2011.

Oct 21, 2026

Solid-State Lasers

Solid-state lasers use a solid crystal or glass host doped with ions such as Nd3+, Cr3+, or Er3+ as the gain medium. First shown with ruby by Maiman in 1960; Nd:YAG at 1064 nm is the workhorse; used in industry, medicine, lidar, and research.

Solid-state NMR spectroscopy

Solid-state NMR spectroscopy applies nuclear magnetic resonance to solid samples, determining chemical structure, three-dimensional structure, and dynamics at the atomic level, reporting on local atomic environments.

Solid-state nuclear magnetic resonance

Solid-state nuclear magnetic resonance (solid-state NMR, ssNMR) is an atomic-level spectroscopic method that determines the structure and dynamics of solids such as catalysts, polymers, and battery materials.

Solid-state physics

Solid-state physics, also called crystallophysics, is the branch of physics that studies rigid matter, or solids, relating atomic structure to electrical, thermal, optical, magnetic, and mechanical properties.

Solid-state polymerization

Solid-state polymerization (SSP) raises the molecular weight of step-growth polymers such as PET by heating solid pellets below their melting point under vacuum or inert gas.

Solid-state power amplifier

A solid-state power amplifier (SSPA) is a high-power radio-frequency amplifier built from GaN or GaAs semiconductor transistors rather than vacuum tubes, widely used in satellite uplinks.

Solid-state reaction

A solid-state reaction is a solvent-free synthesis method in which powdered solid reactants are heated, typically at 500–2000 °C, so atoms diffuse and form a solid product.

Solid-state relay

A solid-state relay (SSR) is an electronic switching device that uses semiconductors such as triacs, thyristors, or MOSFETs to switch a load with no moving parts.

Solid-state sintering

Solid-state sintering is a powder-metallurgy process in which compacted powder particles bond and densify into a solid by heating below the melting point, driven by atomic diffusion.

Oct 22, 2026

Solid-state sodium battery

A solid-state sodium battery is a rechargeable battery in which a solid electrolyte replaces the flammable liquid between electrodes, offering sodium's low cost, improved safety, and higher energy density.

Solid-state synthesis

Solid-state synthesis, also called ceramic or high-temperature synthesis, prepares inorganic materials by heating solid precursors near 900 to 1000 °C, forming oxides, ceramics, and battery compounds.

Solid-state transformer

A solid-state transformer (SST) is a power electronics-based device that converts voltage with semiconductor converters and a compact medium-frequency transformer, adding functions like fault current limiting and bidirectional power flow control.

Solid-state transmitter

A solid-state transmitter is a radio or television broadcast transmitter that amplifies with transistors instead of vacuum tubes, combining hundreds of parallel modules into one output and failing softly.

Solid-state Z-scheme

The solid-state Z-scheme is a photocatalysis design joining two semiconductors through a solid electron mediator, first reported in 2006 for water splitting and CO2 conversion.

Solid–liquid extraction

Solid–liquid extraction, also called leaching or diffusion extraction, is a sample-preparation method that transfers soluble analytes from a solid into a liquid solvent before chromatographic or spectroscopic analysis.

Oct 21, 2026

Solidago

Solidago (goldenrod), Asteraceae genus of about 140 species mostly native to North America; S. canadensis, S. gigantea, S. altissima are invasive in Europe and Asia; S. virgaurea is a medicinal herb.

Oct 21, 2026

Solidago virgaurea

Solidago virgaurea L., European goldenrod, is a perennial Asteraceae herb native from western Europe to Central Siberia and Luzon, type species of Solidago, used as Solidaginis virgaureae herba for urinary tract conditions.

Solidarity

Solidarity, as coined by Émile Durkheim in The Division of Labor in Society (1893), means social cohesion, mechanical solidarity from shared likeness and repressive law, organic solidarity from specialized interdependence and restitutive law.

Solidarity (Ireland)

Solidarity (Dlúthpháirtíocht – na sóisialaigh) is a revolutionary socialist organisation across Ireland, founded 2014 as the Anti-Austerity Alliance, renamed 2017, and allied with People Before Profit in the PBP-S Dáil electoral grouping.

Solidarity (Polish trade union)

Solidarity (Solidarność) is Poland's largest trade union, founded in Gdańsk in 1980 as the first independent union in the Soviet bloc, reaching about 10 million members.